As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHUTDOWN APU WITH APU SWITCH AND AFTER APU SHUTDOWN FAULT LIGHT ILLUMINATED. FAULT LIGHT EXTINGIUSHED AFTER APPROX 5 MINUTES. ACFT GROUNDED. CONFIRMED FAULT, BOTH APU FAULT & APU MX HISTORY PAGE SHOW ECU INTERNAL FAULTS MSG 49-61157. IAW TECH SERVICE REQUEST, R & R APU ECU REF AMM TASK49-61-12, GROUND VERIFICATION, OPS CK NORMAL.