What cell phone parts should I check that would cause 'No Service'?

Dropped my phone the other day and noticed shortly afterward that I could no longer text, make phone calls or use data from my provider because there was no connection to my provider. I've taken the Nexus 5 apart to see if I could assess any damage, but nothing is sticking out. Both antennas are connected well, but I'm not sure what to look for. I had my provider already replace the SIM card and perform a few other tests: disabling GPS/location, etc. Any thoughts would be appreciated. This has been a really great phone.

Best,

David