The red attention indicator light and the toner indicator light are both flashing together

Ready and Error Lights (EPL-6200L only)

The Ready (green) and Error (red) lights on the top of the printer may be the first indication of trouble. The status of the lights, on, off or flashing, indicates your printer status, as described below. The Status Alert window in the EPSON Status Monitor 3 utility indicates what type of error has occurred and offers you a possible solution. Look through this section to find the kind of problem you have, then try the recommended solutions in the order they are presented until your problem is solved.
>

a. Error light (red)
b. Ready light (green)

Status/Error/Warning
INDICATOR LIGHTS
Ready
Error
Service Required (controller error)
OFF
> Service Required (engine error)
> > Service Required (protocol error)
> > Output Paper Jam
> > Paper Jam
> > Paper Out/Feed Jam
> > No Developer Cartridge Installed
> > Wrong Developer Cartridge Installed
> > Installed Developer Cartridge is Not a Genuine EPSON Product
> > Developer Cartridge Memory Error
> > Toner Out
> > Front Cover Open
> > Output Cover Open
> > Printing on Incorrect Paper Size
> > Unsupported Paper Size
> > Time Out Error
> > Insufficient Memory to Print Current Page
> > Paper Size Warning
> OFF
Not All Pages Are Printed
> OFF
Warming Up
> OFF
Replace Photoconductor Unit
> OFF
Toner Low
> OFF
Installed Developer Cartridge is Not a Genuine EPSON Product Warning
> OFF
Sleep mode
> OFF
Ready
> OFF
Printing
> OFF
Processing Data
> OFF
> Note: > If the problem remains after trying the suggestions in this section, contact your dealer or a qualified service representative for assistance.

Service Required (controller error)

Control panel: Error light on
A controller error has been detected. Turn off the printer, wait 5 seconds and then turn it back on. If all the lights come on again, turn off the printer, unplug the power cord, and contact a qualified service representative.

Service Required (engine error)

Control panel: Ready and Error lights flashing
A print engine error has been detected. Turn off the printer, wait 5 seconds and then turn it back on. If the lights come on again, turn off the printer, unplug the power cord, and contact a qualified service representative.

Service Required (protocol error)

Control panel: Ready light flashing, Error light on
A protocol error has been detected. Turn off the printer, wait 5 seconds and then turn it back on. If the lights come on again, turn off the printer, unplug the power cord, and contact a qualified service representative.

Output Paper Jam

Control panel: Ready and Error lights on
Indicates that there may be a paper jam inside the printer. Open the printer's output cover, remove any jammed paper, and close the cover. The error will automatically clear itself and the jammed page's print data is reprinted.

Paper Jam

Control panel: Ready and Error lights on
Indicates that there may be a paper jam inside the printer. Open the printer's front cover, remove any jammed paper, and close the cover. The error will automatically clear itself and the jammed page's print data is reprinted.

Paper Out/Feed Jam

Control panel: Ready and Error lights on
Indicates that there is either no paper loaded in the printer, or there is a paper jam in the feed slot.
If no paper is loaded, load paper into the MP tray, then open and close the printer's front cover. See Loading Paper for instructions on loading paper.
You can clear the error by pressing Continue on the EPSON Status Monitor 3 window that appears.
If paper is loaded, then there is a paper jam in the feed slot. See Clearing Jammed Paper for instructions on clearing paper jams. The error is automatically resolved upon clearing the jammed paper and opening and closing the printer's front cover.

No Developer Cartridge Installed

Control panel: Ready and Error lights on
Either the developer cartridge is not installed or is installed incorrectly. Check to see if the developer cartridge is properly installed and follow the instructions under Developer Cartridge to install or reinstall it.

Wrong Developer Cartridge Installed

Control panel: Ready and Error lights on
Either the installed developer cartridge is defective, or it is not the right one for your printer model. Replace it with a new or correct developer cartridge by following the instructions under Developer Cartridge.

Installed Developer Cartridge is Not a Genuine EPSON Product

Control panel: Ready light on, Error light flashing
The installed developer cartridge is not a genuine EPSON product. The use of such products may damage the printer and cause the print quality to decrease. Remove the currently installed cartridge and replace it with a genuine EPSON cartridge by following the instructions under Developer Cartridge.
To continue using the currently installed developer cartridge, press Continue on the EPSON Status Monitor 3 window that appears to clear the error.

Developer Cartridge Memory Error

Control panel: Ready light on, Error light flashing
A memory read/write error has occurred. Try reinstalling the developer cartridge or replacing the current cartridge with a new one by following the instructions under Developer Cartridge. If this still does not resolve the problem, turn the power off and then on again.

Toner Out

Control panel: Ready light on, Error light flashing
The developer cartridge is out of toner. Replace the developer cartridge by following the instructions under Developer Cartridge. To clear this error and print a single sheet, press Continue on the EPSON Status Monitor 3 window that appears to clear the error. After that, this error will occur again until the developer cartridge is replaced. If you set the Toner Out Error setting to Off, you can continue printing even when this error occurs.

Front Cover Open

Control panel: Ready and Error lights on
The printer's front cover is open. Make sure that the printer's front cover is closed properly by opening and closing it again.

Output Cover Open

Control panel: Ready and Error lights on
The printer's output cover is open. Make sure that the printer's output cover is closed properly by opening and closing it again.

Printing on Incorrect Paper Size

Control panel: Ready light on, Error light flashing
The paper loaded in the paper source does not match the required paper size. Replace with paper of the correct size and click Continue on the EPSON Status Monitor 3 window that appears. If you want to change printer driver settings, click Stop.

Unsupported Paper Size

Control panel: Ready light on, Error light flashing
The specified paper size is not supported by this printer, or the paper feed direction is incorrect. To continue printing from the page after the page that caused the error, click Continue on the EPSON Status Monitor 3 window that appears. If you want to change printer driver settings, click Stop.

Time Out Error

Control panel: Ready light on, Error light flashing
Data transmission from the computer to the printer is interrupted and a timeout error has occurred. Click Print Again on the EPSON Status Monitor 3 window that appears to resume printing. If printing does not resume, or if you want to change printer driver settings, click Stop.

Insufficient Memory to Print Current Page

Control panel: Ready light on, Error light flashing
The printer does not have sufficient memory to print the current page. To continue printing from the page after the page that caused the error, click Continue on the EPSON Status Monitor 3 window that appears. If you want to change printer driver settings, click Stop.

Paper Size Warning

Control panel: Ready light on
The size of the paper that fed through the printer does not match the specified paper size. Click Close on the EPSON Status Monitor 3 window that appears to dismiss the warning.

Not All Pages Are Printed

Control panel: Ready light on
This warning is displayed if an Insufficient Memory to Print Current Page error has occurred while Auto Continue is set to On. Click Close on the EPSON Status Monitor 3 window that appears to dismiss the warning.

Warming Up

Control panel: Ready light flashing
Indicates that the printer is warming up to process and print data.

Replace Photoconductor Unit

Control panel: Ready light flashing (flashes at longer intervals than usual)
Indicates that the photoconductor unit is close to the end of its service life (less that 5%). Prepare a new photoconductor unit to replace the current one. See Photoconductor Unit for instructions.
To temporarily dismiss the warning, click Close on the EPSON Status Monitor 3 window that appears. Resetting the photoconductor unit also clears the warning.

Toner Low

Control panel: Ready light flashing (flashes at longer intervals than usual)
Indicates that the developer cartridge is nearly out of toner. Prepare a new developer cartridge to replace the current one. See Developer Cartridge for instructions.

Installed Developer Cartridge is Not a Genuine EPSON Product Warning

Control panel: Ready light flashing (flashes at longer intervals than usual)
This is a warning to inform you that the installed developer cartridge is not a genuine EPSON product. The use of such products may damage the printer and cause the print quality to decrease. Remove the currently installed cartridge and replace it with a genuine EPSON cartridge by following the instructions under Developer Cartridge.
To temporarily dismiss the warning, click Close on the EPSON Status Monitor 3 window that appears.

Sleep mode

Control panel: Ready light on
Indicates that the printer is in energy-saving mode. The printer goes into standby due to inactivity. If the Sleep mode is enabled, the printer goes into standby in 15 minutes.

Ready

Control panel: Ready light on
Indicates that the printer is ready to print.

Printing

Control panel: Ready light flashing
Indicates that the printer is printing data.

Processing Data

Control panel: Ready light flashing
Indicates that the printer is processing data.

I take it you are refilling the toner cartridge...

Switch the printer off.

Press and hold the green button on your printer and turn the printer on. You will see that the lights flash for a moment and then turn off. After a few seconds, the attention light will turn on followed by ready light and the green light. Keep pressing the green button. In a few seconds, the attention light and the ready light will turn off.

Push the toner rotate button while you continue pressing the green button. As you briefly push the toner button, you will see the light flashing. Release both the toner button and the green button.

Repeatedly push the red button (cancel button). Now all the working lights on the printer will turn off.

Open and close the lid of HP printer once. The light will start blinking.

Press the green button. Your HP toner cartridge chip will be reset.

Switch the printer off.

Press and hold the green button on your printer and turn the printer on. You will see that the lights flash for a moment and then turn off. After a few seconds, the attention light will turn on followed by ready light and the green light. Keep pressing the green button. In a few seconds, the attention light and the ready light will turn off.

Push the toner rotate button while you continue pressing the green button. As you briefly push the toner button, you will see the light flashing. Release both the toner button and the green button.

Repeatedly push the red button (cancel button). Now all the working lights on the printer will turn off.

Open and close the lid of HP printer once. The light will start blinking.

Press the green button. Your HP toner cartridge chip will be reset.

The flashing means that the toner and/or the imaging drum is empty or missing (printing halts on these errors). Lights on steady means low toner.

If the signs that is blinking red which is shape like triangle , it is the toner cartridge indicator. The toner cartridge is empty.Try to pullout and check the toner cartridge, if it is light in weight it is already empty.

If a paper jam occurs while printing, the printer notifies it by the following combination of the four indicators. Remove the
jammed paper . After removal, open and close the top cover once to initialize the jam sensing

Unfortunately, HP didn't make this indicator very descriptive. Their product specification page for this printer states that the blinking Attention light, "indicates that the printer media input trays are empty, the print cartridge door is open, the print cartridge is missing, or other errors".

You've already changed the print cartridge and the light is still blinking, so you should take a look at the other conditions described such as an empty paper tray, open door, and so forth. You also will want to look for a paper jam or carriage jam. These are two very common errors that will result in a blinking Attention light.

HP.com does provide a web page that describes a specific problem associated with a blinking Attention light:

Job Stuck in Queue

See if any of these suggestions work out for you. If not, post back your results along with anything else that you've learned about the problem. Good luck.

From the User Guide:

Black, Cyan, Magenta, and Yellow Supplies Status lights
These lights indicate when a print cartridge is low (the light is on), or empty or missing (the
light blinks). The lights also indicate when a non-HP print cartridge is installed (the light
blinks and the Attention light is on).

If you don't have a User Guide click on the link below and save it for future reference.


2550n User Guide

If this solution has been helpful, please rate it. Thanks!

If you turn off the printer and turn it back on, do you get any noises, ie motor noises, or does it instantly go to all lights flashing?
If you get no noises this usually indicates a board fault and you should look for a new printer.

how do it lits? flashes or permanent? and kindly indicate if its attention indicator or ready indicator...
cause in every flash and lits of that indicators have meaning...