What
@toolmanmike wrote is right on the money.
You can thow darts and hope its just the ammeter, although many times an ammeter problem is not the ammeter at all.
The question is what wiring fried and why.
Although you may know this, many people don't.
The ammeter shows current flow in and out of the battery. The scale goes from 40 amps discharging to 40 amps charging.
Do you recall what the ammeter was indicating at various times during those four hours of operation?
That along with the specific locations of damage will be good clues as to what went wrong.