As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 0472 - ON TAXI OUT AT PHX RECEIVED ECAM MESSAGE FOR AVIONICS VENT FAULT, A BURNING ODOR WAS ALSO NOTICED IN THE CABIN AREA. AIRCRAFT RETURNED TO GATE. MAINTENANCE REMOVED AND REPLACED THE AVIONICS EQUIPMENT VENTILATION COMPUTER IAW AMM 21-26-34, OPERATIONAL CHECK WAS GOOD.