Before going through the altboot method I would suggest updating to the latest firmware to see if it just automagically resolves it without data loss and having to call in a tech.
After the update, Clone it ,if you still can't move on, do an erase customer data , restore via clone like stated by Fabio (Not the scanning stuff obviously)
If you still can't move on, the Altboot, no data backup, no clone method would be required. If you get to that point , send me a PM referencing this post.