As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAINT CREW REPORTS APU BATTERY DEAD. BATTERY SWITCH MAY HAVE BEEN LEFT ON DURING BASE MAINT WITH GRD PWR APPLIED, MAIN AND APU BATT SHOW CHARGING. AFTER 30 MIN BOTH SHOW FULLY CHARGED WITH NORMAL VOLTAGE. BOTH BATT ARE COOL TO TOUCH AND CHARGERS A NORMAL WARM. AFTER RE-CHARGE APU START WAS NORMAL. OK FOR SERVICE.