Black lines appearing on iPad screen?

Hi all. Recently I had to replace my iPad's screen after an accident and it seemed to be working fine. Two days later without warning, there are seven horizontal greyish-black lines on the bottom of the tablet. I tried soft and hard resetting and it isn't going away. Nothing's working. Is it the LCD screen, or maybe something isn't attatched correctly to it? I just want to know in case I need to repair it again.