The device does not seem to detect modem module, which would indicate hardware failure.
Have you tried firmware downgrade? Does the issue persist?
Also, you mention "I have also tried to update it to version RUT2_R_00.07.03.1_WEBUI but it fails the same." Did you mean that you have tried to revert to previous version?
Could you login to the router via SSH and post the output of the command: