[Q] black screen after screen replacement topic

I dropped my phone and shattered the screen. afterwards, the phone started behaving weird, the screen was purple with yellow static, but it still worked. So I bought a replacement screen and replaced it, but after the replacement, the same behaviour persisted. I googled it and found out that it might be the usb flex cable, so I replaced that. After the replacement it worked fine for about half an hour, then it just went black. Now when I turn it on, the backlight turns on, but nothing is being displayed. If I press down on the flex cable connector I get that purple yellowish screen that I had before, but as soon as I lift my finger, it goes black. Did I damage the connector on the motherboard or did I break the flex cable when replacing it?