As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ELECTRICAL BURNING SMELL NOTICED IN CABIN WHILE AT GATE<[01] PERFORMED FIM TASK 21-00 TASK 806 FOR AMM CONDITIONAL INSPECTION 05-51-56 UP TO STEP I. FOUND DEBRIS/DUST IN AFT ENTRY DOOR AREA HEATER & CLEANED PER AMM 21-45-01. CLEANED DUST FROM ALL CABIN TEMP SENSOR FILTERS PER AMM 21-61-06. NO ABNORMAL SMELLS NOTED.