It Won't Power on?

I bought a PlayStation for parts on Ebay and I tested it when it arrived. I knew it probably wouldn’t turn on, but I tested it anyway with the power cable from an Xbox 1 S. It didn’t power on, of course. I then proceeded to open it and inspect the inside. The next morning I spent a few hours trying to find a way to fix it, but I was unable to fix it. I eventually found this website, but their were no answers to my questions.

I believe the problem is with the power unit inside the PlayStation, or the power button on the power unit. Any suggestions?

If there is any details I left out, please tell me!

Okay everyone!

Just a few hours later I was able to fix it! I re-soldered the pins for the power outlet on the power unit and it turned on! There was another problem, but it is unrelated to this topic. Thanks for nothing XD!