2007 Crescendo 8390 CRW - dead as a door nail

[SkiLoWi]

EDIT: Thanks to all for your kind assistance. I now know which battery sets are which and when/how they charge (or not). We've power to start and I've a trickle charger on the chassis batteries to keep them topped off while I continue with the remodel/redecorating. Now on the the next dumb question (in another post) ...

Newbie (and probably, dumb) question -
We've a new (to us) 2007 Gulf Stream 8390 CRW Crescendo mooch-docking in our driveway while I update the interior as per the CEO's "requests." Running a space heater as well as the primary furnace (on low) to keep the interior at a bearable temperature (currently 17-degress here in Utah) while I work on it. We've had it here since the last of October.
I went to start it up yesterday, only to find it sitting deader than the proverbial door nail. Batteries show to be charged and everything 12-volt seems to be working just fine.
No detailed documentation came with the coach, and I've not been real successful in finding anything on the 'net as to which are the house batteries vs chassis ... quite possibly (probably) I'm checking the wrong ones.
I'm assuming (and we all know what that means) the starting batteries are in the bay just ahead of the power bay, while the chassis batteries are located on the passenger side ... does that sound right?
Blown fuse maybe? Where are fuses located?
Any assistance/ideas would be greatly appreciated. TYIA