I have a I2 dual talk mobile and there is a problem in that i can hear a sound in handfree mode only i.e with loudspeeker?

I HAVE A I2 DUAL TALK MOBILE, WHEN I WAS OPEN IT THEN IT WAS SHUT DOWN ITSELF AFTER FEW SECOND THEN AFTER NEXT FEW SECOND ITS WORKING ITS SELF THEN SHUT DOWN BY THIS PROBLEM I CAN USE IT OR NOT ABLE TO WORKING WITH THEM, NO ANY CALL RECEIVED AND NOT OUT GOING.