As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, THE CREW REPORTED AN INDICATION OF SMOKE IN THE CARGO COMPARTMENT THE CARGO FIRE BOTTLES WERE BLOWN. THE AIRCRAFT RETURNED TO ORD AND LANDED WITHOUT INCIDENT. MAINTENANCE PERSONNEL REPLACED CARGO SMOKE DETECTORS AS A PRECAUTIONARY MEASURE AND INSTALLED NEW FIRE BOTTLES. AIRCRAFT WAS RELEASED FOR CONTINUED SERVICE.