As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CARGO FIRE BELL AND LIGHT ACTIVATED AT APPROXIMATELY 20,000 FT. DURING CLIMB OUT. WARNINGS CEASED AFTER APPROXIMATELY ONE MINUTE. ACCOMPLISHED EMERGENCY PROCEDURES AND RETURNED TO DEPARTURE. PERFORMED AN OPS CHECK OF THE CARGO SMOKE DETECTION SYSTEM. OPS CHECKED GOOD IAW AMM 26-15-00-7. NO DEFECTS NOTED.