As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT, APU FIRE WARNING LIGHT AND BELL SOUNDED, FIRE BOTTLE WAS DISCHARGED. AIRCRAFT RETURNED TO LAS AND MADE AN UNEVENTFUL LANDING. INSPECTED AIRCRAFT AND FOUND NO EVIDENCE OF FIRE OR OVERHEAT CONDITION. DEFERRED FIRE DETECT/EXTINGUISHING SYSTEMS AND CONTINUED PER MEL.