As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FIRE INDICATION ON CLIMB OUT. APU WAS NOT RUNNING. PULLED 'T' HANDLE, ISOLATED BLEED AIR, DISCHARGED BOTH FIRE BOTTLES. INDICATION PERSISTED; DECLARED EMERGENCY AND RETURNED TO PABR. REMOVED AND REPLACED FIRE DETECTION CONTROL BOX, IAW SMP581 CHAPTER 26-10. OPERATION CHECK GOOD.