Electrical Issue

We need bolt meter reading!

I hope you are handy with a volt meter.

Locate your converter. Post make and model.
Check converter for reverse polarity fuse.
Use a volt meter to check for converter output.

The Converter of course..

First check all circuit breakers if one is marked conv cycle it (if not cycle all off then back on) now find the converter Sometimes it's behind the breakers (1) other times it is ... Somewhere else (2). The converter has 1 2 or 3 fuses usually 30 amp WITH power off (not plugged in) check them or with power on measure voltage from both of the little square windows to ground Should be the same should be 12.6 or higher if one side is higher than the other unplug and replace all 3 of one side is NEGATIVE the other positive you installed batteries backwards

Finally if it is not putting out between 13.6 and 14.6 you may need a new converter

Progressive Dynamics (Marshall, MI. USA) in my opinion makes the best converters

1: Replace with a 4600
2: replace with a 9200

in both cases try to match the last two digits to the model you have now.

IE a 7460 would take a 4650

Sounds like your converter is toast. Have you checked it?