You may be having a problem with the 50A red self resetting circuit breaker on the wall behind the battery.
Lippert put out a TSB to put the hydraulic system on its own 80A circuit breaker.
Check the files section for threads on this.
It is also published in the Lippert NOW app that you can download from Google play store.
Lots of good info, manuals, and TSBs In the app
https://www.montanaowners.com/forums...id=3&sort=date