Rinse, Repeat
The good news is, Microsoft support is talking to me, and has escalated my case. The bad news: All communication is via their support forums, which seem to have a 24 hour turn around on messages. The other bad news - the first set of suggestions were all of the things I've already tried that don't work. So... I wait for later today or tomorrow, and see if they have any other ideas. In the meantime, my XBox is still effectively a brick.
