Ah so you did not do a clean install by wiping the drive and then installing fresh from either a USB drive or from recovery. Well I have some really bad news for everyone. Apple has done something that has screwed these new MBPs up so bad that you cannot do a clean install of the OS. It gets stuck in a perpetual loop. I dare anyone to try. My machine is being returned tomorrow for a refund. I am beside myself with disgust over this latest fiasco of a release. A train wreck from day one.
Maybe you could try to boot into recovery with a different key combination?: https://support.apple.com/en-us/HT204904