As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAD/SYR - FLT 6585 - DURING TAXI-OUT AT 0530 HOURS, EXPERIENCED A LT FIRE WARNING BELL THAT WOULD NOT TEST. AIRCRAFT RETURNED TO THE GATE WHERE MAINTENANCE WAS DISPATCHED. MAINTENANCE FOUND THE PUSH TO CANCEL BUTTON WAS STUCK IN THE CLOSED POSITION. MAINTENANCE FREED AND CLEANED THE SWITCH ASSEMBLY, FUNCTIONALLY TESTED THE SYSTEM IAW MAINTENANCE PROCEDURES AND THEN RELEASED THE AIRCRAFT FOR SERVICE. (X)