As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA - DESCENDING THROUGH 15,000 FT MASTER WARNING ILLUMINATED WITH CHECK FIRE DETECT WARNING LIGHT ON ADVISORY PANEL AND BTL LOW LIGHT ON APU FIRE CONTROL PANEL ILLUMINATED. ALL 3 LIGHTS CYCLED NUMEROUS TIMES FOR REMAINDER OF FLIGHT. NO ACTUAL FIRE. PLACED SYSTEM ON MEL 26-20-1. RETURNED TO SERVICE.