As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURNBACK/DECLARED EMERGENCY. AFT CARGO FIRE LIGHT FIRE BELL ILLUMINATED, SOUNDED CLIMBING THROUGH 17,000 FEET. PUSHED THE LIGHT & ACTIVATED THE AGENT DISCHARGE & LIGHT & BELL WENT OUT APPROX 5 MINS LATER FIRE LIGHT & BELL CAME BACK ON & REMAINED ON FOR ABOUT 15 SECONDS. DECLARED EMERGENCY & RETURNED TO PHX. REMOVED AND REPLACED CARGO FIRE SUPPRESSION HALON BOTTLE PER MM. REMOVED AND REPLACED AFT CAR FIRE DETECTION ELECTRONICS UNIT PER MM.