Welcome to Android Central! Are you saying that after Smart Switch finished the transfer, the phone unexpectedly did a factory reset? What do you mean by being locked out of Google Play -- are you just unable to access the Google Play Store, or is it not letting up get past the Google sign-in screen before the Setup Wizard?
Google doesn't recognise the new device, log in using your Gmail account from the phone and you should be sweet. Smart switch doesn't move everything over, and things that require passwords, you'll have to set up /log into the first time..