As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING ACCEPTANCE CHECK WITH APU RUNNING, LOUD BANG HEARD FROM REAR OF ACFT. ON WALKAROUND, F/O NOTICED FIRE COMING FROM APU COMPARTMENT. APU FIRE PUSH LIGHTS SELECTED AND FIRE EXTINGUISHED. NO APU FIRE LIGHTS ILLUMINATED. COMPLIED WITH IMMEDIATE ACTION CHECKLIST. APU R & R.