I'm confused by your post. GFCIs and circuit breakers are talking about 120VAC power. Blown/replaced batteries and fuses are talking about 12VDC power.
The common area to both voltages is the converter. You obviously had something drastic going on to blow up the battery. The converter receives the shore power, distributes it as 120VAC through circuit breakers, and also uses it to convert to 12VDC to run operations and charge the battery. If you have lost everything, the converter is the place to look.
Marty and Martha
2015 Z-1 211RD
2012 Nissan Titan