The LCD is really easy to damage and I suspect that this is the case here. Can you post a picture of the screen (add it to your question)? That would allow us to see the “damage” and offer a better diagnostic. As da stunner suggests, it could be a damaged LCD flex but in my experience, they are quite thick and rarely get torn.
The other thing to look at is the LCD connector on the logic board. It has the little flap that must be raised to remove/insert the flex. If that gets damaged, then the flex is not properly tensioned to ensure good contact.