As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RETURNED TO DEPARTURE, AN ELECTRICAL ODOR CIRCULATING IN CABIN. MX FOUND RECIRCULATION FAN 3-PHASE CIRCUIT BREAKERS HAD TRIPPED. RECIRCULATION FAN WAS REPLACED AND THE OPS CHECK WAS GOOD. REPLACED THE RECIRCULATION FILTER AS A PRECAUTION. RAN PACKS WITH BOTH APU AND ENGINE AIR SUPPLY AND NO ODOR WAS IDENTIFIED. ACFT HAS RETURNED TO SERVICE.