Can batteries cause slide issues even when on shore power?

Just a quick note ~~ when we purchased our 2007 Itasca Sunova the salesman doing the 'walkthru' told us to "...have the engine running..." when extending or retracting the slides. which we usually do. Said it gave the Battery a little boost. In my understanding that would be the chassis batt ~ not house batts.

Upon reread ~~OP seems to have a much broader problem. Good Luck.