As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ARRIVAL AT DESTINATION AND DURING TAXI, A FIRE INDICATION WAS OBSERVED WHEN APU WAS STARTED. FIRE DRILL CARRIED OUT, EMERGENCY CREW FOUND NO EVIDENCE OF FIRE AND THE AIRCRAFT WAS TOWED TO GATE FOR PASSENGERS DEPLANE. AIRCRAFT RELEASED ON MEL, APU INOP.