Re: House battery issues
If you know any electricians run it by them.
If you don't, I would take the parts to an RV service center, and replace them all, if possible.
While the relays and other odds and ends are out, check the connectivity of the wiring with a multi-meter if possible.
Beyond that, I'm not sure, but if it's not a relay gate, or a wire/cable, it's probably beyond us all.
It's not a sprint(er) (unless you make it one), it's (hopefully) a marathon.
RV - 2018 Navion 24V + 2016 Wrangler JKU