As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAULT ON TAXI-IN. REMOVED AND REPLACED APU BATTERY IAW AMM 24-31-04. APU BATTERY VOLTAGE CHECKS GOOD. ALSO REPLACED APU STARTER IAW AMM 49-41-01 OPS CHECK OK. APU BATTERY OFF PART: PN 018550-000, SN 121356. THIS CLEARS MDDR 129070.