No network service with clean imei

Hi

I got a dropped S4 with no network connection. I tried different SIM card, I tried the SIM card in another phone (and they worked), I've flash the phone, I've check the imei statut (it is clean not blacklisted).

Possible Sofware solution remaining: Reflashing the EFS

Possible Hardware solution remaining: Too many

My question is: do you thing it's hardware or software related and depending on your answer what do you think it could be?

Thanks a lot for your time!

Max One