Probably best to plug a trickle charger in and leave it overnight .
You could jump it but todays computer controlled vehicles do not take kindly to sudden voltage changes.
I also have a 2016 Vegas and had a dead chassis battery, once.
After that I put a knife switch on the chassis battery and disconnect it whenever the coach is going to sit.
All of these rv's seem to have mystery draws on the chassis battery , you can try to hunt them down or just disconnect the battery when not in use.
Sounds like your house batteries may be dead as well . Plug your shore connection in , make sure your battery switch by the entrance door is in the "use" position and that should charge the chassis batteries.
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