phone dead no one willing to help from apple.

Apple, my brother bought apple 5 4yrs ago on a contract from mtn. It only worked for 18months and it died. He went back and forth from one apple store to another amd was told to go back where he bought it without any help. Till today . Last year we took it to a repair shop to try amd fix it and he was told that it cannot be fixed. Is it posible for a phone to die without any explanation. Also was any apple store suppost to hlp him. Can this be factory fault or what do we call this. I know its been 4yrs already but there must be explanation atleast. Can some1 hlp plz.