As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU GEN INOPERATOR. GROUND RAN APU AND FOUND P5-4 PANEL GEN SWITCH FAULTY. REPLACED P5-4 PANEL, REF 24-21-51. GROUND RAN APU IAW 24-21-00. PERFORMED OWR OPS CHECKED. GROUND RAN ENGINES 1 AND 2. TRANSFERRED POWER MANY TIMES. APU DID NOT DROP OFF LINE.