almost everything has 12v controls, wired to the house batteries
no DC power, nothing will work, expect the MW, no fridge, no heat,no A/C, no water pump ..etc..
generator can be on either house batteries or chassis, depends on the builder
the aux start is usually powered from the house side so if the start battery is dead, the house batteries pull in the relay, the house side is dead so it won't work 'yet'
but start the engine, let it idle ten minutes, then hit try the aux start with the generator
if you get enough power into the house batteries to get enough voltage to pull in the aux start relay, you can possibly get the generator started