When you say "the entire coach did not have power" you have to tell us what power.
There is 120 VAC Shore Power (SP)
There is 120 VAC Generator Power
There is 12 VDC battery power - which can also be supplied by SP or the Generator regardless of the position of the USE/STORE switch.
And it appears your coach may also have 120 VAC Inverter power to some circuits, which is powered by the house batteries.
The USE/STORE switch does not disconnect the Inverter from the house batteries.
The USE/STORE switch does not need to be in USE to start the Generator, but it must be in USE for either the Generator or SP to charge the batteries.
To start the generator you must have:
Good, charged house batteries
The positive supply cable properly connected to the batteries, and
The 100 Amp DC breaker that supplies 12 VDC from the house batteries to the Generator for starting must not be tripped.
So it sounds like you parked the RV without being plugged into SP and either left the USE/STORE switch in USE or left the Inverter on (most likely) and drained your house batteries.
Many people complicate the problem when they replace the house batteries either by not reconnecting the batteries correctly or by tripping one or more of the DC breakers - the 50 Amp one to the DC buss, loads and charger, the 100 Amp one to the Generator , or the breaker/fusible link to the inverter.
Hopefully this helps.
Ted & Melinda
2016 ACE 27.1
2016 Chevy Sonic Toad
2020 Chevy Colorado Z71 Trail Runner Alternate Toad