As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
A BURNING ODOR WAS SMELLED IN THE CABIN DURING CLIMBOUT OF EWR. THE AIRCRAFT WAS RETURNED TO EWR WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE AVIONICS EQUIPMENT COOLING FAN SHORTED OUT. NO EVIDENCE OF FIRE WAS FOUND. THE FAN WAS REMOVED AND REPLACED IAW MM 21-58-12, OPERATIONAL CHECKS WERE GOOD.