As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX - FLIGHT 2345 - ON PUSHBACK AND ENGINE START, APU BATTERY CHARGER STATUS MESSAGE RECEIVED. RETURNED TO THE GATE. MAINTENANCE REPLACED THE APU BATTERY CHARGER IAW AMM 24-32-07-000-801-A02 AND OPERATIONAL CHECKS GOOD IAW 24-32-07-400-801-A02. AIRCRAFT RETURNED TO SERVICE.