What was found
ABORTED TAKEOFF, SHORTLY AFTER TAKEOFF ROLL, EN ROUTE, THE AFT CARGO DOOR INDICATED OPEN, REJECTED TAKEOFF AND RETURNED TO GATE. MAINTENANCE FOUND DOOR SECURED, APPLIED MEL 52-70-01, COND. 8, AND VISUALLY VERIFIED DOOR SECURE. UPON ARRIVAL, MAINTENANCE CLEANED AND LUBRICATED DOOR LATCH MECHANISM, CYCLED DOOR A DOZEN TIMES, DOOR INDICATION WAS GOOD.