Welcome to the Forum from Western New York State!
I'm only able to throw out thoughts on your problem, so the first one is, since you say every outlet works, then the problem lies in the 12 volt side, which is the lights and slide motors. There has to be power to the breakers in order for the 110 volt side to be still working unless it's an inverter, and it's depleting the batteries trying to power the outlets/ microwave, etc. Since there's a fuse of some kind near the battery, it's 12 volts also. Now, I'm thinking there's a dead short that's causing that fuse to blow on contact. Maybe something wrong with the generator transfer switch. It's going to take some tracing, and investigating to find that. What did the mobile tech do, or say while he was working on it?
These are only my random ideas, since I don't have a generator, or inverter system. Good luck, and keep us up on what you may find.
If you're going to "regret it in the morning", sleep until noon.
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