As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 4669 WHILE ON THE GROUND THE CREW REPORTED A BURNING ODOR IN THE COCKPIT AND THE FLIGHT ATTENDANT NOTICED A "SULFUR SMELL" IN THE MIDDLE OF THE CABIN. THE AIRCRAFT WAS REMOVED FROM SERVICE. PERFORMED GENERAL VISUAL INSPECTION. RAN APU AND PACKS FOR SEVERAL HOURS. FOUND ODOR COMING FROM SIDEWALL BALLAST. REMOVED AND REPLACED THE BALLAST IAW AMM 33-31-09. THE AIRCRAFT WAS RETURNED TO SERVICE.