As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FINAL APPROACH, THE APU FIRE LIGHT ILLUMINATED AND BELL SOUNDED. THE FIRE BOTTLE WAS DISCHARGED. INSPECTION FOUND NO SIGN OF FIRE AND THE BOTTLE WAS REPLACED. TROUBLESHOOTING FOUND THE FIRE WARNING LOOP 'A' TO BE AT FAULT. THE ELEMENT WAS REPLACED AND OPERATIONAL CHECK OF THE APU AND FIRE WARNING SYSTEM CHECKED OK.