As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAILED TO START 3 TIMES, 1ST ATTEMPT WAS ABORTED DUE TO A STANDBY POWER CHECK. REPLACED APU BATTERY. APU CONTROLLER DISPLAYED SLOW STARTS AND ACCEL FAULTS. BATT VOLTAGE BELOW 13 VOLTS & NO CHARGE. ACP BATTERY & APU TESTS, BOTH OP CHECK NORMAL. FAULTS CLEARED, APU NOW OPERATIONAL.