As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER PARKING AT THE GATE & OPERATING PACKS WITH APU BLEED AIR A STRANGE ODOR ENTERED THE FLIGHT DECK, A BURNING ODOR. OPERATED APU BLEED WITH PACK SYS NR 1 & NR 1 SEPARATED FOR ABOUT 15 TO 20 MINUTES BETWEEN FULL HOT & COLD & NO SMELL STRANGE ODOR AT THIS TIME IAW AMM 21-20-00. ALSO OPERATED BOTH ENG BLEED AT 90% OF N2 WITH PACKS ON & NO ODOR AT THIS TIME IAW AMM72-00-00.