As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING GROUND POWER. NOTICED SMOKE FROM APU COMPARTMENT. FIRE DETECTOR LIGHT ILLLUMINATED. MANUALLY DISCHARGED FIRE BOTTLE. RED DISK DID NOT DISCHARGE. R & R 2449-K62 RELAY IAW MM 24-31-09. PN ON AND OFF AJ-A4N-176. R & R START GENERATOR FOR APU IAW WC 24-30-02R. REACTIVATED SYSTEM, RAN APU, OPS CHECKED GOOD.