Lost GSM service after fall

I have an Edge 20 which suffered a heavy fell and got slightly bent. All seemed fine, I carefully bent it back to flat shape but then GSM service started being unreliable and in 1-2 days got lost completely.

Additionally there is a small crack near the On/Off button and a bit of exfoliation on the back glass panel.

All other wireless connections (WiFi, Bluetooth and NFC) work fine, but there is constantly some unusual heat around the NFC location.

SIM cards are detected, but no more signal/service.

Could someone give me a hint about which component could be the root cause of the defect?