Our xerox workcentre 4150 is stuck in a self test mode. We have turned off the machine and unplugged it several times, and it keeps going back to the message Please wait....Machine self test in progress. What should we do?

Hi Cnorini ,
Check this video and solve your problem.
In Case You Still face Problem and Need Online Assistance Then Please Follow Us For On : Xerox Printer Support

If your Xerox WC 4150 is displaying "Clear the Jam in the Print Engine" or constantly jams as paper exits the machine you should check and possibly replace the fuser actuator (part# 120N00534) This is the most likely cause, if however this does not fix the printer the next step may be to replace the sensor or fuser.
Here is a video that shows you how to check and replace the actuator. ItemInc.com has this part in stock and ships same day. Good luck, and thanks for using FixYa!
">

This one probably relates to a failing CMOS battery 105N02093. First, though, you can unplug this battery for 30 seconds and try again. This is an inexpensive part, so start with the battery.
It could also be a defective hard drive 005N01086 or Main board 140N63141.

Whit
Item, Inc

It varies from machine to machine. There are at least 6 differnt ways to access service modes that I can think of.

You have to twist them clockwise and then counter clockwise. There is a locating pin they stick on in back, All I can say is twist and pull.
You can try opening the right side door and sliding a thin bladed screwdriver in there to assist in lostening it .
That is not uncommon and is frustraiting.

Check and see if your using the PS driver for that machine, If so switch to the PCL driver. The PS one has been known to run slow.

1. From the WorkCentre, enter the Tools mode. See the Related Items below for additional information. The Tools Mode screen will be displayed.
2. Select [Software Reset] from the Touch Screen.
3. Select the [Reset System Software] button. A popup window will be displayed warning that jobs on the machine may be lost and asking for a confirmation before the reset is performed.
4. Select [Confirm]. The WorkCentre will reboot the system software.

One of 2 things.
EIther you have to enter the Fax User memory, Or the memory battery has failed and needs replaced.
Here is what the service documentation says.

(4150) During a power-off period, the machine has lost its user memory. Check that the backup battery, PL 1.10 Item 5 is holding its charge of about +3V. If necessary, install a new battery, PL 1.10 Item 5.

That is usually a bad main board. You can try removing the memory and reinstalling it...that fixes the problem sometimes. Also unplug your network cable and turn it on...data present when turning on some xerox models will cause problems.

Main Board is part number 140N63141

Sorry I didnt see your post a while back.
You shold call and have the firmware updated on that machine.
There are several firmware updates to the 4150 that resolve a lot of problems with the machine/.