ERROR 53

Have tried everything to first upgrade iPhone 6s would not upgrade--phone froze with iTunes logo and plug on black screen--tried to restore as upgrade did not work on iPhone 6s only goes halfway on iTunes and than stops and gives error 53--will not allow to force shut down --so frustrating as I have no working phone even to make any outgoing calls or receive incoming calls --have apple MAC and this is last time I buy anything from Apple!