Default Reception issues after drop

I bought a Note 2 right when they came out. Around January I dropped it and shattered the glass, then brought it to a repair shop to replace the display assembly. Cost $150 or so, and they were very professional. Ever since the drop though, I feel as though it's only getting about 60% signal, and it has a very very hard time finding signals and locking them. It drops calls constantly, and says "Searching" probably 40% of the time.

I took it apart and all of the antennas appear to be intact, with good connections. Everything on the phone is flawless except the radio.

Recommendations? It seems stupid to buy a new Note 2 for $450, and I can't get a phone without T-mobile WIFI Calling because I work in a building that is massive (and a signal hole for all but Verizon) and I NEED to be able to receive calls and texts coming to my Tmobile number.