As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FIRE INDICATION AFTER START AT 12,000 FT. PULLED FIRE HANDLE AND THE LIGHT REMAINED ON. AFTER FIRING THE BOTTLE THE FIRE HANDLE LIGHT WENT OUT IN ABOUT 2 SEC. APU HAD BEEN RUNNING FOR ABOUT 1 MIN WHEN THE FIRE INDICATION CAME ON. TROUBLESHOOT SYSTEM, NO TROUBLE FOUND.