Replaced screen, boots fine, but does this weird thing

So I recently replaced the screen on a Sony Xperia z3. Everything went well, I made sure all the connectors were seated properly (I think) and it displayed fine. For the first 3 seconds.

After that the colors seemed to spread in lines, particularly vertically. To check if it was os related I turned it off. But even the battery symbol does it. Picture of the thing

Anyone know what's going on?