DS top screen is just white, possible damage from capture card?

I've had my DS phat with a capture card for several years, I've had to do some repairs on it every now and then but right now I'm having an issue that I'm not sure how to fix. It was working as normal and suddenly the top screen was pulsing white. I tried disconnecting and reconnecting the screen ribbon cables (I have a capture card, I tried both with and without the capture card) and now the screen was just white with no other picture. I thought the screen might have broken so I tried replacing it with another screen which I knew was working, but it had the same issue, with and without capture. This made me think the connector on the motherboard was broken. After replacing the mother board and trying again (with the newly replaced top screen), it was still just white with no picture, with and without capture card. I also tried replacing the ribbon connector board in the top shell, and it was still just white. I didn't try it with the capture card because I think that my capture card is causing the issue. It might have broken/shorted and causes something to break or short in the motherboard or connectors. I'm probably going to get a replacement DS and capture card, but I wanted to post here to see if anyone has any other ideas. Any help is appreciated.

EDIT: I put all of the original parts back in my DS and it still doesn't work (which makes sense). I put all of the original parts back in my spare DS (where I got the other top screen, motherboard, and top screen connector that I knew worked), and everything works fine. So I know all these parts work with each other, but when I try them in my DS, still just white screens. I'm really not sure what could be the problem but I'm going to keep looking into it, and use a voltmeter.