2018 RT Simplicity inverter issue/DOA

[PhilmontP]

Newly acquired 2018 RT Simplicity. All electric systems worked until it didn't. Shore power connected but no 110 works inside and it doesn't charge 12 volt battery. I know there is power going through the power cord. No solar system. The battery is drained. If I drive the RV the alternator begins to recharge the house battery. The 15 amp GFI breaker above the drive seat is tripped and unable to reset. Not sure what that circuit does? I want to assume it is the 2000w Microgreen Inverter. Unable to test 110 AC input for power in back of inverter without partially removing inverter. Not sure on next step? Thoughts?