Sim card is not connecting to the network

[Android Central Question]

Ive just purchased an X6 Pro Doogee phone that had android os 5.1 upgraded to 6.0. But I cannot connect to an netwofk. Wifi is working ok but the radio is not. What can the fault be?

 

[Rukbat]

Something wrong with the upgrade? Something failed in the phone? There's no way to diagnose it without having it.