Dark Screen with Flickering Lines, Otherwise Works Fine

Hello, I have the HP Edition 20 gb Ipod 4th generation, model # MP102. Previous to this issue, I had replaced the hard drive inside it with compact flash solution at 64 gb, replaced the battery, hold switch assembly, and, in trying to fix the issue, replaced the screen. It had worked fairly well and easily for about a year prior to this issue arising.

As for the issue itself, it's as described in the title. The screen commonly boots into a black square, which renders it unusable. If it does not do this, visible flickering lines appear regularly in any moving image on the screen.

I've attempted several ways to fix the issue; none have seemed to work. First, I replaced the screen as mentioned earlier. Then, I attempted to clean the inside and the logic board with isopropyl alcohol, although I honestly had no idea what to look for when doing so. The iPod had not been exposed to any liquid at all in the year I'd had it. I also tried to restore it twice, but each time the issue would reappear as soon as I turned it on.

My assumption is that the logic board is fried. Anyone who has had similar issues, or who knows more about this issue, your help would be much appreciated. Thank you!