As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FIRE BOTTLE DISCHARGE LIGHT ON. APU FIRE BOTTLE LOW ON PRESSURE, SO APU RENDERED INOP. *S/D* APU FIRE EXTINGUISHER WAS FOUND TO HAVE LOW PRESSURE. REPLACED THE APU FIRE EXTINGUISHER AND RELATED SQUIB PER 757MM 26-22-01. PERFORMED OPERATIONAL CHECK AFTER REPLACEMENT PER SAME 757 MM, AND FOUND THAT SYSTEM CHECKED OK.