Make certain that you have a good 12 volt supply to the generator; even if you have to connect a jump box to it. If it still will not turn over, you will need to start diagnosis starting at the switch to starter solenoid to starter.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7