As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER LANDING, STARTED APU WHICH STARTED NORMALLY AND THE BLUE APU GENERATOR BUSS LIGHT ILLUMINATED BUT THE APU WOULD NOT TAKE AN ELECTRICAL LOAD. VOLTS AND FREQUECY BOTH SHOW ZERO (BLANK). PERFORMED OPS TEST FOR THE APU AC GENERATION AND CONTROL IAW AMM TASK 24-21-00-700-803. OPS CHECKED GOOD, UNABLE TO DUPLICATE, NO HISTORY IN THE PAST 30 DAYS.