Agree that the Genesis is junk. I replaced mine with a home receiver and consider it one of the best "mods" I have made to the RV.
I assume that all of your other 12v devices are working (lights, water pump, etc.)?
Do you have access to a 12v tester of any sort (multimeter, test light, etc.)? Checking for 12v at the fuse seems a lot easier to me than trying to track down other inline fuses/circuit breakers etc. The 12v circuit likely is protected at the battery and or the converter, but there would almost certainly be many more items on that same circuit breaker/fuse (lights, etc.). In a pinch, you can take any 12v device and use it to test for voltage at the stereos fuse.
'04 GMC Sierra 2500HD, CCSB, D/A, MaxBrake, B&W Companion, Retrax Pro, AR Power Steps
2021 Solitude 310GK w/FBP
1969 Camaro RS/SS Convertible
Dad's old 1968 Empi Imp (recently recovered from under 21 years worth of boxes/dust)