As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED A CARGO BOTTLE LOW CAUTION MESSAGE ON CLIMBOUT OF CLT. CREW ELECTED TO RETURN TO CLT AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED AND DEFERRED THE CARGO FIRE EXTINGUISHING SYSTEM PER MEL 26-25-01. MAINTENANCE REMOVED AND REPLACED THE CARGO FIRE BOTTLE IN ACCORDANCE WITH THE AIRCRAFT MAINTENANCE MANUAL. MEL WAS CLEARED. AIRCRAFT WAS RELEASED FOR SERVICE.