Your 120v breakers and your 12v fuses and charge converter are separate systems
Contained in one box
You have to disconnect from shore power
Open the box
And disconnect the 120v for the charger part, only the charger part
You need to leave everything else connected
It's clear that you need another person that knows how to do this
Once this is done
You have to have another way to charge and maintain your batteries
Install another stand alone converter and connect it to the batteries
Or
Use a portable battery charger, doable but not the best option
