As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU WON'T START. REPLACED BATTERY, CHARGER TWICE AND K116 ALL NO HELP. CAL BATTERY CHARGER REMOVED AND RETURNED TO CAL. FOUND PIN 9 OF D302 BENT AND SHORTING CAUSING BATTERY CHARGER TO SHUT OFF. REPAIRED PIN AND CHARGING SYSTEM CHECKS OKAY.