Hi to everyone, i would like to update my question and how i fixed the issues, so i fixed the issues by replacing the usb connector board (bought on a famous auction site) and after that you have to (sadly) re-assemble the complete case in order to your mobile network work fine.
The latest step is really important because in the backcase (inside) there are the antenna's flex's (the white one) otherwise you are unable to get any mobile data, so is not like the other smartphones. Hope this will help someone.