As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT CREW REPORTED A BURNING ODOR EMANATING FROM THE AFT CABIN. DURING INSPECTION, IT WAS DISCOVERED THAT THE CONNECTOR TO THE TRANSPONDER CONTROL UNIT IN THE INSTRUMENT PANEL SHOWED SIGNS OF OVERHEATING AND MELTING. CONTACTS APPEAR TO HAVE SHORTED CAUSING THE OVERHEAT CONDITION.