iPhone 6s No Service issue after screen replacement?

I recently replaced the screen on my 6s and the display works fine but after wiping and restoring the OS (screen was freaking out and disabled the phone before I replaced the display, had never synced to iTunes) I can't connect to a cellular network. I tried a new sim card and after factory resetting my phone again I was able to connect to my network (Sprint) for about an hour before I lost it again and haven't connected since. I have reset the network settings, reset the date and time, and tried to access Field mode but it wont connect. SIM is still recognized when ejecting, leading me to believe it is an antenna issue? Really need to figure this out, any help is appreciated!