What was found
FLIGHT RETURNED TO A NORMAL SAFE LANDING BACK AT ATL DUE TO A BURNING SMELL IN THE CABIN. CABIN CREW VERIFIED THAT NO SMOKE WAS VISIBLE IN THE CABIN AND NO SMOKE DETECTORS WERE SOUNDING, BUT A STRONG NOXIOUS ODOR ("GARBAGE OR ELECTRICAL") PERSISTED. NO MENTION OF ANY SYSTEMS BEING SECURED. MAINTENANCE COMPLETED A BORESCOPE INSPECTION AND NO DAMAGE WAS REVEALED. DUCT BURNOUT WAS ACCOMPLISHED, COALESCER BAGS WERE REPLACED, AND THE AIRCRAFT RETURNED TO SERVICE.