I just updated to 1.3.5.1 and did not have any problems. However, a friend of mine is trying to update right now and his Pre locked up.

My update took only a few minutes and his has been locked up on the "Updating the system/Do not remove battery" screen for about a half hour.

Any suggestions? Obviously, removing the battery is a bad idea. But if the phone locked up and the update is broken, how does he move forward?