I have a 2-3 year old HP DX2080MT which was working fine till now, except for a known problem that we could not use pen drives on the USB ports (used to crash). Well, yesterday I must have forgot and plugged a pen drive in to the front panel USB and immediately got a blue screen (running WindowsXP).

Now the PC will not boot at all, not even the BIOS screen (no video signal). When I press the power button the power comes on (fans, lights) but no boot and not even any system beeps (I removed RAM, mouse/keyboard and HDDs). Removing the battery did not help either.

Really appreciate any help getting out of this. Thanks.

If you have a test meter and know how to use one then testing the outputs of the PSU might be worth doing.

To power the PSU independantly, you need to unplug it from everything internally, you then need to short the green wire to any black one with a paper clip or something similar. Next, set your meter to 20 volts DC, attach its black probe to any black wire the test the following.

Yellow, should be 12 volts.
Red, should be 5 volts.
Orange, should be 3.3 volts.

If the PSU doesnt power up with the link fitted or any of the voltages are a long way off then your PSU needs to be replaced.

Hope that helps!