As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING BOARDING OF THE FLIGHT ROC TO IAD, CREW REPORTED SMOKE COMING FROM THE COFFEEMAKER, CFR WAS DISPATCHED AND PASSENGERS RETURNED TO GATE. MAINTENANCE PERSONNEL REMOVED AND REPLACED THE COFFEE MAKER AND AIRCRAFT WAS RELEASED FOR RETURN TO SERVICE.