No Service After Housing Upgrade

A few days ago I transferred my iPhone parts to a black + gold rear housing, and everything was perfectly fine until today when I took it to work. The majority of the time it says "No Service", and hangs when there is service. However, when I take it upstairs, it works perfectly fine. Everything was also working properly when I was at home. Any idea what I could've done wrong? Prior to this T Mobile was connecting just fine here. There were one or two screws I put in the wrong place (like a 1.5mm screw in a 2.1mm pot), as well as some screws left over. Maybe I scratched a resister off?