Go to the dealer, if they want to charge you for it, Get Hyundai USA involved. they know there is a problem with this knob. Let them know you are going to contact NHTSA about faulty wiring that can catch fire.
Want to know what it looks like back there?
They don't have to open up the whole dashboard. If they honestly believe that, you need to start taking your car someplace else. The V section around the head unit pulls out (2 slots near the bottom of the V for a pry tool), the switch is easy to get to. Try cleaning it. If it is seriously heat damaged, report it like others have mentioned, as it could be a potential cause of a future fire, and/or try a replacement unit from a junkyard