iPhone 5s Screen issues after repair/ Won't connect to iTunes

I recently bought a iPhone 5s off eBay that had the Error 40 iTunes error. After attempting to fix it and put it back together, the Screen now has a white line horizontally at the very top, and a bunch of purple squares everywhere else. It also seems to restart itself every once and a while. It also won't connect to iTunes, but will charge when I plug it in. I need to get this fixed asap. Also, where could I find a logic board link cable and repair a gps cable?