As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOR FLIGHT 4090 DURING INSPECTION FOUND THE HALON FIRE EXTINGUISHER IN AFT CABIN MISSING A SAFETY PIN AND WIRE (YELLOW BUTTON STILL PRESENT). THE AIRCRAFT WAS REMOVED FROM SERVICE. RE-SECURED SAFETY PIN AFTER LOCATING IT IAW ETN GN-26-001R1. THE AIRCRAFT WAS RETURNED TO SERVICE.