I have a 2nd generation Apple TV. I just installed the 5.1 update. Unfortunately I had lost my remote for the Apple TV but that wasn't a big deal because I had my iPhone set up to control the Apple TV.
However, I cannot click the continue button after the update. I can hear the interface scrolling around "behind" the update, but not actually clearing the screen. I can also play music from the remote, but the screen stays at the update screen.
Help! How can I dismiss the feature update screen?!
I had this same exact issue and while frantically searching for a solution the screen suddenly disappeared and everything is back to normal. So hopefully for anyone else experiencing this issue, 5 minutes or so of waiting is all it will take.