Same thing happened here and my solution was:
1) create a bootable usb with the createinstallmedia method specified before
or
2) use option command after trying the regular way and boot from the image that the update 3 procedure left after installing
that should do the trick and don't be surprised the system will boot several times! Be cautious though and do not try this on a production system.
SteveRokette
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution
From
Doetinchem, Nederland