The contact owns a 2021 Keystone Arcadia Fifth Wheel 3660RL. The contact stated that while the fifth wheel was being towed, the brakes became inoperable. The check wiring and trailer connected check message was displayed. The contact stated there was abnormal whining and tapping noise detected. The contact called the local dealer who informed the auto-reset breaker was causing the noise. The contact's wife called him and informed him there was an abnormal burning odor in the vehicle and it caught fire. A person at the RV park was able to unplug the Fifth wheel from the power unit. There were no reported injuries. The fire department extinguished the fire. The police were on the scene and a report was filed. The front battery and wires were fired and damaged. The vehicle was towed to an independent lot. The manufacturer was notified but no further assistance was provided. The failure mileage was unknown.