As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE BATTERY EXPERIENCED AN INTERNAL SHORT CAUSING THE TERMINAL POST TO MELT. ONCE CONTACT WAS BROKEN, THERE MUST HAVE BEEN A SPARK CAUSING A FIRE. DAMAGE SUSTAINED WAS A BURNED BATTERY BOX LID. NO RECOMMENDATIONS CAN BE MADE FOR PREVENTION. NO CAUSE COULD BE FOUND. A NEW BATTERY WAS INSTALLED AND ALL SYSTEMS CHECKED NORMALLY AND FULLY FUNCTIONAL.