I own a 4G router MR6400 (V2) and a couple of days ago I tried to update its firmware to the latest version. The firmware is not even sent to the router. The web interface goes blank. I made sure the firmware was the correct one (triple checked).

So I went ahead and attemp to factory reset it to clear any faults/errors that could be the issue.

Try to factory reset it from the router web interface returned an Error Code: 20.

Trying to factory reset by pushing the WPS/RESET button more than 15 seconds doesn't work either. I even tried to use the 30/30/30 approach and nothing seems to work.

I'm not able to factory reset the modem.

Has anyone faced a similar issue or knows what the Error Code: 20 means?

Thanks