"mfleming".....Two things....when a Magnum Inverter display acts up, the typical remedy is to go out to the inverter and disconnect what looks like a telephone line from the side. Count to ten and then plug it back in.
If the batteries are working okay and everything else is functioning, it would seem that the batteries were reconnected correctly, but there are often some sensor wires from the inverter that connect to the batteries and may have been connected wrong. One of the sensors is for heat and usually connects to the side of the battery bank to tract temperature.
Don & Mary
2014 Newmar Dutch Star - All Electric - 450 ISL
2016 GMC Canyon 4WD Crew Cab