MR1100EUS dead after firmware upgrade

My MR1100 upgraded it's firmware to latest version (12.06.12.00) and lost connection after it. I managed to get it back up by booting without SIM and manually entering apn info, which had been erased. It worked until the next reboot. Now it just loops between logo and loading "circle". Reset does nothing, no matter how long I press it. Removing SIM doesn't help, power source doesn't matter, tried several and battery. 

Only way I can do anything, is via EDL mode and manually uploading older firmware, but that doesn't help either.

It's a 400€ modem, so I'd expect it to last a little bit more than 2 years and not break down when automatically upgrading...