Trunk Wiring problems of the 2008 Ford F-150

2008 f150 supercrew lariat 4x4 bought brand new on July 18 with 426 miles on it. I have made no modifications to the truck except put a flat bed cap on the bed that attaches with clamps under the bed rail and has no electrical components. I have driven the truck less than 2500 miles. On the morning of the incident I drove to work just minutes away from home. Parked truck and locked vehicle and went into factory to my office. 35-40 minutes later I received a call on my phone from the guard building saying my truck was on fire. I walked back out to the parking lot and the truck was filled with smoke. Bystanders said truck had flames inside going up windshield but had died down. They had a fire extinguisher but the truck was locked and they didn't want to open the truck since the flames were dying down until the fire department arrived. Fire department arrived and I unlocked truck door and opened up truck to let smoke out. Small fire rekindled under dash on passenger side, put out immediately with dry chemical fire extinguisher. Opened hood to disconnect battery cables for fire department and did not notice any damage in engine compartment. Interior dash was completed burned away in a 4-5" wide area between radio/hvac control console and glove compartment door. Area that includes the auxiliary power plug and a dash vent. I made no changes/modifications or add ons to the truck after purchasing the vehicle, and had nothing plugged into the auxiliary power plug at any time. Dash is completely gone in this area plus a small portion above the passenger airbag area of dash. Vent is completely gone, auxiliary power plug is completely burned away with just a metal frame of the plug remaining laying on the floor of the truck on top of some melted, piled-up plastic from dash. No wiring was attached to the metal frame anymore. Fire department made a report, so police were not called to the scene. Ford consumer department was notified but declines liability.