White screen, to power off. Need help.

So I have fixed a couple ipod 4g screens and such. But I am having trouble with one. I made all the repairs and connections with no problems at all. I plugged it in and it worked great for a couple of minutes. Then it just white screened on me. I tried DFU mode but it turned off. Computer won't recognize it. Won't do anything when I plug it into the wall.

Reconnected all cables to the screen but I cannot even get the white screen now. The ipod won't even turn on/screen will not display a thing. Wondering what could be the problem.

I'm stumped. If there's any help you could offer it would be greatly appreciated.