As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ELECTRICAL BURNING SMELL IN FLIGHT DECK AFT OF CREW SEATS. R & R LT AND RT RELAY SUPPORT PANELS AND LT & RT CONTACTOR PANELS. PERFORMED GVI OF RELAYS & CONTACTORS. NO DEFECTS OR SMELLS NOTED. REINSTALLED PANELS. FOUND SMELL TO BE MAIN BATTERIES. BATTERIES R & R. RAN ACFT FOR 15 MINS. NO SMELLS NOTED AT THIS TIME. A/C OK FOR SERVICE.