Yes, you should shut off your battery kill switch when the RV is not in use and is not plugged in, or connected to a battery charger/maintainer. There are small draws that will continue to be pulled otherwise, like the LP detector, some smoke or carbon monoxide detectors, and circuit boards that use 12 volt power such as the one in the refrigerator.
It sounds like your battery was drained all the way. If it is not a sealed type, check the water levels, and if low, top up with distilled water. Then either plug in the RV to shore power to have the converter charge up the battery, or charge it yourself separately.
After it is fully charged, you can have it tested. Good luck!
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