Gateway SX2840 Power Supply in Limbo

Gateway SX2840 (small form factor) PC with Windows 7 Home 64 bit, using internal video.  Worked well for about a year, but front USB ports stopped working.

Opened case and discovered a couple of loose connections for the USB ports.  Seated cables and reassembled case.

Reattached power cord, video cable, keyboard, & mouse to test.  Fans spin up on power supply & CPU, very little HDD activity (less than 5 seconds, then nothing), no video.

I disconnected everything, checked all connections again, still nothing.  Gateway's site suggested disconnecting power cord, holding down power switch for 10-15 seconds to drain system, then powering it back up.  They then tell me to power off when I see the POST.

However, still no video.  Monitor does work with a laptop.

I've tried removing the HDD and optical drives, but get the same result.

Is it possible I've toasted the power supply or maybe just really annoyed it?  It's a bizarre shape and really tiny so it's not something I'll be able to replace easily.  Just want to make sure there's nothing I can do to "reset" the power supply before I spend any cash on it.
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Dr. KlahnPrincipal Software EngineerCommented:
You might try troubleshooting it as a stripped motherboard.  Unplug the power supply at the wall.  Disconnect everything from the motherboard except the keyboard, video, CPU fan and power supply.  Disconnect everything else - audio cables, disk drives, USB connectors, everything.  Remove and reseat the memory.  Pull the BIOS backup battery; if there is a BIOS reset jumper, set it and replace it; otherwise, wait 5 minutes.  Reinstall the backup battery making sure it goes back in the way it came out.  Plug the power supply back in.

This is about as naked as the system can get and still show whether it is functional.  Now power up the system and see if it gets to the BIOS self-test screens.  If it POSTs, the chances are that one of the cables that was disconnected was installed backward.

If it doesn't, there's a possibility that the power supply or the motherboard was damaged.  In that case, the best diagnostic is a POST 4 card, if there is a PCI slot available.  If not ... at that point it's swap motherboards or swap power supplies to confirm which has failed.

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it looks like you may have dislodged a card or connector
inspect, and remove all cards, and connectors, and reinstall them properly - also RAM

another possibility can be bad capacitors -check for bulging or leaking ones
the minimum setup - as decribed here, can help you to troubleshoot further :                  (Short-overview-of-how-to-troubleshoot-bad-hardware-when-a-pc-does-not-post)
mbuttsAuthor Commented:

Thanks, I hadn't tried pulling the RAM + battery.  I was able to get it to boot to W7 after following your procedure.
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