Welcome to the forum and irv2, Ken.
will lead you to all TSB;s ,brochure, owners guide and othe info for your coach.
will explain your BIRD System for all your batteries.
All the links below in my signature have more info for your Newmar.
As Gary said you need to charge your house batteries, check the water levels if wet cells, charge for over 24 hours with a good stand alone battery charger.
Dealers do not continually charge batteries while coach is on their lot, yet they keep using them to extend your slides and low batteries will get slides in trouble always use GEN or shore line.
If the batteries come back to life and you have at least 110 at home plug your shore line in and you BIRD System will keep all your batteries fully charged.
As Gary said you need to test them with no external power and just read across the batteries need 13.5 or close.
With the BIRD System working and your converter supplied the 110, charging voltages will be between 13.5 and 14.5 volts.