As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURNBACK, ON CLIMBOUT FROM BDL AFT CARGO COMPARTMENT FIRE LIGHT ILLUMINATED, ALONG WITH FIRE BELL. PER QRH DISCHARGED BOTTLE. APPROX 4 MINUTES AFTER DISCHARGING BOTTLE, FIRE LIGHT EXTINGUISHED. OVERHEAD FIRE CONTROL PANEL SHOWS SCU FAULT WITH AMBER LIGHT. REMOVED AND REPLACED SCU.