artic fox 811 on 2005 dodge ram 2500 diesel short bed??

So the switch near the sink is on --still no power. He already checked fuses. The issue the man was discussing about probs fitting the 2016 3500 drw is more than I can even take. Seeing we just sold truck today and have a 60k truck ordered trying to do the right thing. It shouldn't be this complicated! The only 6.4 box in a dodge 3500 drw is a megacab. So I guess I'm just going to have faith the camper dealer can make it work and fix this fan problem.