iPhone 5 Screen Going black after replacement when put in frame

After repairing a customers iphone 5 and verifying the new screen functioned properly I put it back into the frame and it immediately goes black when I out the top right corner of the screen in place. If I leave just that corner slightly out it works fine. I dont know what could posibly be wrong. I thought it was the ambient light sensor thinking it was next to a face causing it to go black but I cannot confirm and dont see how just that corner would be affecting it that way,