The contact owns a 2015 Coachmen Prism Motor Home built on a 2014 Mercedes-Benz Sprinter 3500 chassis. The contact stated while driving at an undisclosed speed, the BBQ compartment door independently unlatched and landed in front of the exhaust. In addition, the contact stated the BBQ compartment door and the interior which were made of Styrofoam, and the plastic latch, were melted. The vehicle was not diagnosed or repaired by an independent mechanic or the dealer. The manufacturer was made aware of the failure but provided no assistance. The failure mileage was approximately 67,000.