With the shore power cord un-plugged, start at the house battery bank, verify good voltage 12.5 or higher and check 12vdc + and 12vdc - connections. Make sure you have a good chassis ground then follow + cable to fuse or circuit breaker making sure you have good voltage through it to the battery disconnect solenoid (usually located in Battery Control Center). Then check the disconnect to be sure voltage is passed through and is feeding through any fuse or circuit breaker to the distribution panel in the coach. The next test point will be the main fuse(s) in the distribution panel. Finally make sure you have a good ground connection from the ground bar (usually behind the distribution panel) to chassis frame ground connection. Good luck and keep us posted.
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