Depends how you did it. Have your dropped it in water or have you dropped etc. It could just be the screen which has disconnected so book it in for warranty repair. I have to keep fixing my mums a51 as it keeps disconnecting as she drops it lots 😂
I don't know on that to be honest. I would have it printed if you're going to Samsung direct just to be prepared but I think they can tell off the imei when the phone was activated. You should be okay mate.