I ran a dual battery system for a while back before LED lighting was what it is now. Only damn thing those dual batteries were good for is killing batteries two at a time and becoming a fire hazard. I went through 8 yellow top optimas real quick and pulled that crap out. Haven't missed it since, and my batteries now last years instead of months. With most of these inexpensive solenoid-activated systems, when one battery goes bad, the next one won't be far behind, and you won't know until its too late.
Sorry I could be of much help, but in my opinion you'd be better off boxing it up and sending it back. Rugged Ridge makes a good amount of money selling cheap, knock-off versions of popular mods. Some are decent, this one is not. It's nothing you can't go buy at the local Napa for even less, they just supply all the wiring to make it convenient, and tack on some profit.