The most likely issue is also the easiest to fix -- is the battery disconnect button pushed in? It's on the control panel. If it is pushed in, the battery will not charge.
Let us know if that is (or is not) the problem!!
2012 Fun Finder X-139 "Boondock Style" (axle-flipped and extra insulation)
2013 Toyota Tacoma Off-Road (semi-beefy tires and components)