What was found
AIR TURNBACK AFTER TAKE OFF, CABIN WOULD NOT PRESSURIZE. OUTFLOW VALVE WAS INDICATING "CLOSED POSITION". CABIN INFLOW LOW ALERT. FOUND FWD CARGO DOOR AFT LATCH NOT LOCKED LATCH RESTING ON TOP OF AFT LATCH FITTING. COMPLIED WITH MM TASK 52-31-01-820-801 2B, HORIZONTAL ADJUSTMENT WITHIN LIMITS. FOUND AFT LOWER LATCH PIN DAMAGED AND OUT OF ROUND. REPLACED AFT LOWER LATCH PIN IAW DWG 5913031 REV, ADJUSTED IAW AMM 52-31-01. OPS GOOD. PRESSURIZATION CHECK OK.