"No SIM card - No service" error message after upgrading Android

After upgrading Nexus 5 from Android 5.1.1 to 6.0.1 cannot make outgoing phone calls or receive any calls as "No SIM card - No service" message, even though SIM card works on other phones.

Please let me know if anyone has the solution to this. Have spoken to service provider (T-Mobile) and LG and they just keep me running around in circles between the two of them.

Very frustrating!

Thanks in advance for any help possible for this issue..