As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RIGHT BEFORE ENG START, BOTH APU GENS DROPPED OFF LINE, FOLLOWED BY STRONG ELEC ODOR. INSPECTED APU COMPARTMENT TO VERIFY NO DISCREPANCIES, NO DISCREPANCIES FOUND. VERIFIED NO ELEC ODORS PRESENT WHEN BOTH APU GENS OFF LINE & APU PNEUMATICS WORKING.