As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FUME IN ATL DURING BOARDING, ODOR OF UNKNOWN ORIGIN IN THE CABIN. DEPLANED PAX. SMALL HYD LEFT HORIZONTAL STAB LEADING EDGE HYD PIPING WAS FOUND AND REPAIRED. APU REPLACED PRECAUTIONARY DUE TO EVIDENCE OF OIL INGESTION. OIL DE-CONTAMINATION PROCEDURE WAS ACCOMPLISHED. AIRCRAFT FAILED THE VERIFICATION TEST FLIGHT. FURTHER TROUBLESHOOTING, NR 2 ENGINE WAS AT FAULT AND REPLACED ON LOG PAGE 0194470.