Could be several issues:
ensure that you have the disconnect switches for the coach and chassis batteries turned on so that you have power, you can check this at the generator with a multimeter.
Then check to see if the generator starts from it's own control panel instead of the remote panel if you haven't already done so.
If you have 12v at generator, check for 12v at the gen starter during start procedure, if you never get 12v at the starter then you could have a bad switch, relay or control board. So work backwards from the starter checking for 12v at each of these components.
That is the simplest method of tracking down an electrical issue.
2014 Fleetwood Discovery 40G -> '16 Yukon Denali
Mechanical and Electrical Engineer
"De Opresso Liber"