As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING RAMP TAXI FLIGHT, CREW AND PASSENGER NOTED SMOKE IN AFT CABIN. GENERATOR AND ELECTRICAL SYSTEMS SHUT DOWN. PASSENGER DEPLANED. BAGGAGE COMPARTMENT OPENED AND AUXILIARY BATTERY FOUND SMOKING. IT HAD HAD A THERMAL RUNAWAY AND WAS MELTED. NO OTHER DAMAGE.