Why are there dead spots in my screen after replacement.

Hi there, My phone recently fell and i got it fixed. Unfortunately i brought it to someone who made a botch attempt at fixing it, long story short the keys u, n and j dont work. The screen also glitches out sometimes and opens up stuff randomly. So i decided enough was enough and brought it to a professional. He was very helpful and did a good job, i posted it too him but left my pass code on it and when i received it back he left a message saying he couldn't open it to check if it worked. After using the iPhone for a few minutes it was clear that all the old problems still remained. I contacted him and he said he would look at it. Has anyone on here got any suggestions