As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(LOG 4638769) BOARDING AIRCRAFT, STRONG ELECTRICAL OZONE SMELL IN COCKPIT ALSO STRONG IN FWD LAV. FOUND SMYD 2 TO BE THE SOURCE OF SMELL. NO POWER AT SYMD 2. REF LOG 4638768 FOR R/R. R/R LT & RT RECIRC FAN FILTER PER B737 AMM 21-25. RAN BOTH PACK NO SMELL.