12 volt system not working

[Texas 250]

I have a 2015 34 RESA, unplugged from main power and 12 volt system did not work, hydraulic jacks, slides and refrigerator would all work when unplugged from main power but all lights, water pump and awnings would not work, when I plugged back up to main power or ran generator all lights, water pump works, replaced 6volts battery last week due to age, had no issues after replacing, any ideas on what is going on. Thanks