I performed the update yesterday (6/20/12) and it seemed successful as I was able to play FIFA 12 afterward. However, after I turned off my Xbox, I was unable to get it to restart. The console will begin to load, then freeze on the white start-up screen.
I have performed the steps of the support article on "freezing" (can't get to the option to clear the cache as it won't load, also tried removing the hard drive which didn't help) and also tried pressing the sync button while turning the console on as suggested in a previous forum post.
Any help would be greatly appreciated!