Generator voltage poweres the inverter charger which charges the house batteries. The inverter/charger will charge you chassis batteries if you have equipment to make that happen. My coach came with an Echo Charger that routes charging current to the chassis batteries once the house batteries reach full charge.
Regarding your boost switch, you chould have 2 big cables on the boost solenoid - one to the house battery bank, one to the chassis battery bank. If those cables are in place, and the solenoid is working, but you coach still won't turn over, then I expect one of the cablles that goes on the chassis battery positive post is the root of your problem.
FWIW, when I bought my coach, the echo charger was hooked up worng. The solid red lead goes to the house batteries, the yellow and red lead goes to the chassis batteries.
If you determine that your boost solenoid isn't working, you can use your chassis batteries to start your coach by connecting a battery jumper cable from the positive of one bank to the positive of the other bank. You need a good jumper cable for this. Small cables will get warm in a hurry.
Check you battery nergative connections too.
I recently made and installed new cables in my battery compartment. The cables in my 2001 were the original ones, and they were not in good shape. When I did the project, I put in a couple of buss bars, one for the positive house power, one for the chassis house power. This let me get the spagetti wiring off the battery posts, and made it easier to insure I have good battery connections.
Here is the chassis battery positive posts before my project:
My battery compartment after project:
Here is an illustration I made fo power distribution in my coach. I'm sharing here because it shows the charging circuits.