Can you get power to it?
You'll need to put some jumper cables on the house batteries, and get enough charge in them to get your Use/Store switch set to "Use" (or on...)
Once you get that set: plug into some 120, and let those batteries soak up a really good charge.
You should then be able to use your emergency start switch to tie the house batteries to the chassis battery. Start it up, and let the alternator make some magic happen...
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