Again, thanks everyone for the comments and suggestions.
Learned a lot about batteries in so short a time. Forgot that we have an electrical engineer and someone who works on batteries (Tesla), lol.
Forgot too the conventional wisdom among scientists. That if you are finding solution to a problem, look at the simplest first. The advice I got, first, check the terminal connections if loose and 2nd, check the battery if it's gone bad.
And my problem indeed is the battery. As my in-house expert said, 2 to 5% of those will be bad right out of the factory floor -- and unfortunately, a few will not be detected in quality control and testing and will end up in our hands and mess up our time under the trees and with the mountains.
Lwiddis is right, batteries have life cycles and will die if it reach it's limit. Our RV's deep cycle batteries are meant to go on deep discharge, hence, the name, duh. It is not supposed to die or go bad immediately if it's fully discharged, but the deeper the discharge, the shorter the life cycle. Extreme heat is also the enemy and so as residues falling at the bottom and accumulating to touch plates.
And yesterday was the more difficult task. I must have made more than a dozen calls to the CW dealer, salesman, service department, Dutchmen (manufacturer), battery dealer... for anyone to honor their warranty.
In desperation, end of the rope post for, Ella/Ask Marcus. Wish me luck!