What was found
PASSING FL250 ECAM WARNING ALERT FOR MAIN DECK CARGO DOOR UNSAFE. RTN TO DEN AIRPORT. NO SIGN OF ACTUAL UNSAFE DOOR. WARNING STOPPED AT 500 FEET ABOVE GROUND. RELEASED FOR SERVICE PER MEL/CDL: 52-71-01 CATEGORY: C EXPIRATION: 29JUN07 "MEL 52-71-01: MAIN CARGO DECK DOOR CLOSED AND LOCKED INDICATION ON ECAM DOOR PAGE, INOP. MAIN CARGO DECK DOOR VISUALLY CHECKED CLOSED AND LOCKED. [07-03-07] ADJUSTED SWITCH 49WS USING TEST BOX 35M5M01160001 REF A300 M/M 52-71-11-5-02. ALL INDICATIONS NORMAL AT THIS TIME. ITEM CLEARED A/C OK TO CONT.