As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU AUTO SHUT DOWN. TAXI CREW TRIED STARTING IT SEVERAL TIMES WITH NO START, BIT OF APU CONTROLLER SHOWED NO ACCEL IN POSITION 1 AND OVERTEMP IN POSITION 4 THRU 5. REPLACE APU BATTERY CHARGER. APU SLOW TO GET TO SPEED AND DUCT PRESSURE 10 PSI.