Hi - first off, while I'm very familiar with working/troubleshooting on modern PCs, I've recently gotten into retro stuff, and there's a heap of stuff I have to learn.

I bought a Gateway 2000 P5-75 off of eBay, and the seller's description said that it seemed to work fine. When I turned it on immediately after receiving it, it would rev, but nothing displayed on the screen, and the HDD light was off. I looked inside and found the video card (S3trio32) wasn't in correctly, so I snapped it back into place. I took out the ribbon cables connecting the hard drive and CD drive so I could check to see if anything else was wrong, and not being able to find anything, put them back. When I turned it on, now the HDD light turned on, but it just stayed on from the second I pressed the power button without blinking at all - nothing displayed on the screen still, and that's essentially where I'm stuck now.

Here's a video of it, well, not doing anything when I turn it on. Will the constantly-on lights and lack of certain normal boot things happening give anyone an idea as to what's (not) happening, so I have something to go off of? For note, I can't see any damaged parts. No burst capacitors, nothing bent, it all looks fine (to me).

Here are some pictures of the inside; not sure if they're going to do anyone any good: