I had the same issue with the same model inverter on my new 2022 Heritage Glen 369BL which I took delivery of a couple weeks ago. It started at the solar controller. I was getting an over voltage error code on the controller so I started opening the battery boxes and measuring voltage at the batteries. Voltage at the batteries was fine. Took the controller off the wall and measured voltage at the solar input terminal and the battery terminal. Readings were erratic. Then realized the battery wires were connected to the solar terminals. And the solar wires connected to the battery terminals. Swapped them. And the solar controller comes to life and operates correctly. Great. Inverter still not working. Iím getting a bit ticked off because this thing is brand new and my first camper. I start tracing the wiring from the inverter to the batteries. And thatís when I notice the black, negative wire connected to the positive post on my secondary battery. Moved the negative wire to the negative post and voila. The inverter turns on.
So. My point in explaining all this is, donít trust the factory hooked up your electrical wiring correctly. And donít trust the dealership did a proper delivery inspection of all the components installed on your camper.
Should I have caught the solar controller error code during my delivery walk around? Yes. And I did and I pointed it out to the dealership. But after a nightmare delivery day, I forgot to go back to check the controller before leaving the dealership.
If I ever buy a brand new camper again, the dealership is going to hate me after I go through everything with a fine tooth comb.