HP a820n No Power-up after City Power Failure

probably ur battery is dead or your loading circuit is malfunctioning, due to internal circuitry overload most like to overheating.

Usually the light will time out after the capacitor has drained. Your machine is getting a bit old , your PSU may be the problem. If you plug it in and push the on/off button and it blinks, fans spin and shuts down, it's most likely the PSU. Look for a in-line fuse on the Motherboard, if blown, replace. Look at the motherboard closely for damaged components, capacitors, etc.

The green LED light at the back of the Power Supply, is now a diagnostic LED light.

Tells you the Power Supply is bad.

HP Support > Pavilion a1020n Desktop PC > Main Support page,

http://h10025.www1.hp.com/ewfrf/wc/product?product=459880&lc=en&cc=us&dlc=en&lang=en&cc=us

Solve a problem > Start-up / Shutdown / Power >
(No Thanks) > Power management,

Scroll down. Click on the + sign to the left of the blue -
Power supply light is on or flashes

(When the PC worked the green light stayed on constantly. You are correct)

Now,...
1) Is the computer dirty inside? Need to know how to properly clean it?
2) Would you like to know the easy test, to see if the problem may be a $5 ATX power on switch, or the Power Supply?

3) I also suggest you remove all ram memory modules, ('Stick'), and clean their gold plated contact pins, with an eraser.
There is a proper procedure for this.

Post in a Comment if you wish to know.

Regards,
joecoolvette

{By the by. Did you or your father live in K.C.K, (USA), and does the name Philip B., ring a bell? }

Is better fix to buy on.Theirs a lot good inexpensive model.Best Buy,COMP USA,EBay,etc...

I have the same model computer and had the same issue. There are a couple of things to check out with both being fairly simple. If possible go ahead and replace the power cord just making sure to replace it with a cord of the same specs which could come from another device such as a printer. The next area to check out is inside the case and here you just want to remove any dust build up and make sure to clean the fan at the power supply. To open the case you only need to remove the two thumb screws on the back side opposite the power cord then pull the side towards you and it will pop off. To clean it you can use a can of compressed air to blow it out, there really shouldn't be any need to disconnect or remove anything. This should prevent it from shutting down and not powering up.

make sure nothing is plugged in to your front card readers slots:
If so PC will not boot. Other then that can you put a different power supply in it? Just to see if it is the Power supply..

Yes,the LED power lite on the front panel stable?Yes,mean the DM power supply board is good.LED power like blinking,mean the DM power supply board is dead.DM power supply is good,still making that clicking sound,when turn on.Mean ur Blast board is dead,that the board that help to light up the projection lamp.

was it dropped..?? the indicator light should b solid not flashing.. If you held the power switch in for several min an nothing Try plugging the cord directly into the wall. Do not use power strips as they may have failed.Toggle the voltage regulator switch from 115V to 230V then back again. If you are in North America, this switch must be on 115V. you may have a loose connection in the machine Lastly, you may need to go inside the case and confirm the thin wires running from the front power and reset switches are connected to the motherboard., to check be sure u are grounded an check all connections inside the computer... If the LED is still flashing, the power supply is probably bad.

Try these steps.
If Power supply light does not turn on (or no power supply LED)
Perform the following steps, in order, until power is restored or it is determined that there is a hardware failure:
NOTE: If the Power Supply fan spins when the PC is turned on but the light does not come on, it is possible the LED is defective. If this is the case, use the section Power supply light comes on or flashes .
1. Disconnect everything from the PC, including the power cord.
2. With the power cord disconnected, press the power button on the front of the computer. Plug in the power cord and test to see if the computer can turn on. If not, continue using these steps.
3. Replace the power cord with another power cord, like the one used by the monitor.
Test to see if the computer can turn on. If not, continue using these steps.
4. Ensure that the voltage selector switch is on the correct setting, 115V for North America.
5. With the power cord removed, flip the red voltage selector switch to the opposite position, wait about five seconds, and then switch the red voltage selector switch back to its original location.
This ensures that the voltage switch is engaged and set correctly for your country/region.
6. Plug in the power cord and test to see if the computer can turn on. If not, continue using these steps.
7. Plug a lamp into the same outlet to see if the wall outlet has power. Try the computer in a different outlet in order to eliminate the outlet as a possible source of the issue. Test both to see if the wall outlets have power.
8. Remove all extension cords, power strips, surge protectors and any converters that remove ground. Plug the power cable directly to the wall outlet. Test for power. If this fixes the issue, find the device that is causing the issue and do not use it.
9. Use a vacuum cleaner to remove the build-up of dust from the power supply fan vent holes. Make sure that the PC is turned off and that the power cord is plugged into a grounded outlet. Only use the end of the vacuum hose near the outside of the fan entrance.
Plug in the power cord and test to see if the computer can turn on. If not, continue using these steps.
10. If all of the above steps have been tried and the power supply light remains off, use the steps in the next section, use the next section Power supply light comes on or flashes , to reseat the cables and check the power switch connector.

Hi Franceso, plz specify
Is it powering ON ?
Which LED is glowing?
These leds are there on the front panel :

1 Power On/Standby button
2 System power LED
Green = Power on
Amber = System shut down, but power still applied
Off = No power

3 Internal health LED (Wave sign in BOX)
Green = Normal
Amber = System degraded. To identify the component in a degraded state, refer to system board LEDs.
Red = System critical. To identify the component in a critical state, refer to system board LEDs.
Off = Normal (when in standby mode)

4 External health LED (power supply)
Green = Normal
Amber = Power redundancy failure
Red = Critical power supply failure
5 NIC 1 activity LED Green = Network link
Flashing = Network link and activity
Off = No link to network.
6 UID LED Blue = Activated
Flashing = System remotely managed
Off = Deactivated
7 UID button

If it is Internal health led then any internal h/w issue is suspected.
If it is external health led then any power supply or power source related issue is suspected.
Also check the status of the server & its IML (Integrated Management Logs) in ilo (Integrated Lights Out ) if it is configured. (2nd RJ45 port in rear)

Also make sure the cabinet is properly closed.