I’m assuming you mean that when plugged in to external a/c outlet you get power, but when you unplug and expect to automatically switch over to battery power you are dark. I don’t have an Aria, but if you run your generator do you get power to the coach? I suspect yes and that your a/c side of things is good, and that sound you heard was something tripping on the d/c side, either fuse near the battery bank or even on/near your inverter. More details would help. Here’s a basic Thor breaker vid.
https://youtu.be/ZutspydomZM
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