Does you coach have a chassis batter isolation switch, did you turn it off while you were changing batteries???
If it does have a switch cycle it off and on and see if the power comes on.
Last year my switch failed, I had no chassis power. I took switch out and tested, no continuity across posts no matter how I turned the switch. Bolted the 2 batter cables together to be able to start the coach. Ordered replacement switch, installed, and all is good.
2002 Monaco Windsor 38 PKD
2005 Jeep Grand Cherokee w/5.7 Hemi