[Q] Screen not coming up after replacing LCD and mainboard topic

Hi all, I have a Galaxy 10.1 GT-N8013 that started having issues with the screen, it would flicker and show colors distorted, etc... then it went completely black. So I replaced the LCD. the problem didn't go away. When I turned it on it had sound but the screen was black. Then I thought my diagnosis was wrong and it wasn't the screen but the mainboard. So I got a new mainboard and replaced it but it didn't help either. The issue is the same - black screen but has sound.

I would appreciate help solving this mystery.