Agree, loose wires and low voltage, either one can cause that sort of damage. That is why the caution above that warranty might be denied unless you can prove installation error, which is going to be tough.
Either way, it is imperative that you get any melted/burned wires replaced, as they are now their very own fire hazard.
Given the horror stories about bad electricity at campgrounds, folks should at the very least have a volt meter to check and preferably monitor the power pedestal. A surge protector or even better, an auto former, is a good idea.
While you are at it, don't forget a water pressure regulator. One campground we stayed at warned everyone at checkin that the city water supplier insisted on delivering water at 150 psi, and not to hook up unless you had a regulator, as that pressure will burst every line in your RV. At another campground we were assigned a site at the bottom of the mountain, with their water supply at the top. The pressure from our hydrant was so high the nozzle-less white hose shot a stream of water a good 50 feet. I dunno what the pressure was, but it was well over the 80 psi RV plumbing is rated for.