Original post by: Sunny ,
When they replace the whole assembly. they transfer the Touch ID over from your old phone. thats why the design of the Touch ID is so easy to remove. Because the monkeys at apple need to transfer it over, yet somehow they manage to rip it. if that happens they will have to replace the phone for you for free! The Touch ID is serial coded to the logicboard. apple does this out of spike because they hate DIYers.