HP Z420 shutdown after startup

[Audiokontrol]

HP Z420 shutdown after startup.

The hdd lights up green. Powerbutton is not working.

No matter how long I hold the power button (20seconds), the computer will not turn on, only the green HDD LED will glow continuously green.

When I pull the power cord, the HDD LED will stop glowing after 10 seconds.

When I reconnect the power cord, the computer will automatically turn on and after 2-3 seconds the computer turn off. The green LED lights up again.

No beeping.

Battery removed from the motherboard, graphics card & ram removed, did not help unfortunately.

Does anyone have an idea what it could be?

Thanks!

[DGroves · Accepted solution]

if the system starts up, then   immediately shuts down the cause is usually a defective power supply or a motherboard issue that is power related

(if it gets to the windows loading screen, then the issue is a corupt OS, reinstall)

try removing all pci-e cards (including video) disconect all hard drives, and remove all ram 

you want nothing connected to the power supply except for the bare motherboard

then try powering on, (ignore any flashing lights or beeps due to missing ram)

does it power on and stay on longer this time?

if so add just the minimum of ram and retest (you want to add parts back one by one testing each time till failure)

if not then it's most likely the pwr supply or motherboard

[Audiokontrol]

All steps done. Still the same issue. Just Powersupply to motherboard connected.

It seems that the motherboard or powersupply are not working anymore.

I'll try to replace the powersupply.

Thanks for your help!

[Audiokontrol]

I cleaned the computer from dust (it was not sooo dusty) and the workstation is working now. 

I can't believe it was the dust.

Thank you anyway.

[DGroves]

sometimes just unseating/reseating all connections can fix a power/no start issue

one would think that appon seeing a massive dust buildup in a computer that cleaning it would be a good first step and that mentioning a large dust buildup when asking for help might also be a good idea

remember folks, the quality of the help received is based on a large part ,.. what information "YOU" provide