As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING APU START, THE APU FAILED TO START. WHEN BATTERY SWITCHES WERE RETURNED TO AUTO CREW REPORTED A STRONG BURNING ELECTRICAL ODOR. MEL WAS ISSUED AT THIS TIME. MAINTENANCE COULD NOT DUPLICATE DISCREPANCY. AN OPERATIONAL CHECK OF THE APU SYSTEM WAS COMPLIED WITH NO DEFECTS NOTED. AIRCRAFT WAS RETURNED TO SERVICE. (M)