That's a late 3G unit. Have you checked the config to ensure it knows what it is? One peculiarity with the 3G units is they keep their config in an external serial eeprom, and it's not unheard of for it to lose its mind and default to believing it is a US 750VA unit. That screws all the configs and calibration constants and causes it to think it's overloaded, boil the batteries and other nasty things.
Read up on how to config those units, put a serial cable on it and check before you go suspecting the hardware. Or of course you could just dive in and start ripping apart, shot gunning parts and making wild guesses