PSP1001 Powers with Green Light But No Display or Audio

I recently got a PSP1001 off of ebay as an as-is untested device. I already knew I was going to have some issues with the system and it definitely needed repair from the listing alone, but I can't quite place what's up with it.

I haven't done a full teardown because I was still testing the basics. I replaced the battery, got a new memory stick pro, and I recently replaced the screen just in case that was the issue. It looked like it was one of the issues previously, but I'm back at square one with no idea what's wrong with it.

I tried powering it up without the memory stick, powering it up without the battery, I tried holding the power and the bumpers R and L buttons, all of that and all alike. It's not a software issue I don't think. However, without me doing a full teardown, it's hard to point what is wrong hardware-wise.

All I need right now is suggestions on what I should look at next at this point. Thanks!