HP Compaq Elite 8300 ultra slim desktop will not power up

[fsab820]

When I press the power button, nothing happens.  No lights turn on the front panel.  Computer does not turn on.

[mdklassen]

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@fsab820 wrote:

When I press the power button, nothing happens. 

No lights turn on the front panel. 

Computer does not turn on.

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Start at the electrical wall-outlet.

Is your computer plugged-in to that outlet?

If so, unplug it, and plug in a lamp, or the recharger-brick for your mobile phone -- does the lamp light up, or does the phone show "charging" ?

If so, then that outlet is not the problem.

Or, if a power-bar is plugged-in to that outlet, unplug it, and try the lamp and the mobile phone.

By the way, does the power-bar have an ON/OFF switch? Did you accidentally turn-off the power-bar?

Next, some computers have a rocker-switch, near to where the power-cord plugs-in to the back of the computer.

Be sure that the switch is not in the "off" position.

If "none of the above", then your computer has a problem:

* dead power-supply,

* dead motherboard,

* dead processor.

It is not easy to "test" any of the above components.

Tell us the results, after you check the above, and we can go further.

[fsab820]

Hello and thanks for responding.  I checked the wall outlet with a lamp. Outlet works fine.  PC was not plugged into a power strip and there is not a rocker on/off switch on the PC.

What I have done is unplugged the power supply from the back of the PC, pressed the power button for 15 seconds, removed the cover from the PC to expose the internals, then plugged the power supply back into the PC then into the wall outlet.  What I observed is a tiny green LED light glowing on the motherboard.  I pressed power button again but nothing happened. 

[mdklassen]

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@fsab820 wrote:

plugged the power supply back into the PC then into the wall outlet. 

What I observed is a tiny green LED light glowing on the motherboard. 

I pressed power button again but nothing happened. 

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Very-slight possibility: broken power-button.

The power-supply outputs several different voltages.

So, the voltage that powers that LED seems to be OK.

But, that does not indicate that the other voltages are OK.

Try to disconnect the leads to the disk-drive, and to the CD/DVD device, and try to power-on.  Probably, no difference.

Is the original HP Warranty still valid?  If so, HP will repair/replace your computer, at no cost.

If it is not valid, then HP can still fix it, for a fee.

My best guess: failed motherboard.