Sm-g920p- qcn file needed?

I’m not receiving reception, the phone is unlocked and I wrote a cert and it’s indicating that the cert is OK. Network Status UNBLOCK and IMEI Pass. Do I need a QCN file for the phone to work correctly? It read the SIM Card for 1 second, and then it lost signal and it says SERVICE: Limited. I’m not sure if the certificate isn’t clean or if I’m required to repair QCN. CAN ANYONE Help with a QCN file for SM-G920P?