Try a Target disk:
If you are buying a new mac, Apple will do the migration for you, I would let them do it.
If you have an external monitor, I would try to do a data backup before doing anything.
Could also be your drive has already failed, or logic card. Again I would take it the Apple store, and have them deal with it since you bought a new Mac, they would do this for free, and the shoulder the responsibility.
Hoe this helps.