SAMSUNG GALAXY S3 I747 UNLOCKED @ RS. IN INDIA

Up for Sale is SAMSUNG GALAXY S3 i747 (AT&T Version)UNLOCKED SMARTPHONE IMPORTED Display don't turn Up,i don't know why ?Touch is responding (we can hear sound),if you CALL Bell RINGS (See Video Below) and if you swipe CALL connects.ALARM Kept  also RINGS,Two physical keys near HOME Button light ups Tried to Connect to SAMSUNG KIES,it say SCREEN LOCK. (Its not a problem because if it get a Good Display can USE OTG cable and unlock) If i had a Extra SAMSUNG S3,i would have change Display and OPENED LOCK SCREEN and tested more. Questions ? 1.Why Selling a Product of US Carrier