As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER DEPARTURE MCI (1000 AGL) CARGO DOOR LIGHT ON SOLENOID PANEL ILLUMINATED. RETURN TO DEPARTURE AIRPORT. CABIN PRESSURE WAS LOST WHEN LIGHT CAME ON. ADJUSTED LOCK BAR CLOSED SWITCH AND 1 LOCK SWITCH. MAIN CARGO DOOR OPS CHECKS GOOD PER MM 52-32-1. (M)