The Cliff's Notes®...
So here's the short-and-sweet of the matter...
Getting your Sense to break out of the reboot loop and actually restart requires precisely two things: 1) a buttload of patience, and 2) SHEER DUMB LUCK while pressing, holding, releasing, re-pressing, re-holding, and re-releasing the side "button" until you eventually hit the sweet spot between looping reboots, where an actual "restart" can take hold.
The full(er) story...
A lot of people apparently have (or had) the "Sense reboot loop" bug (and, Yes, Virginia, it is a bug!), including myself. I encountered it today when I tried to start the Exercise > Walk app, which would only display the Exercise icon for about a second, before returning to the clock face.
After this happened several times, I was prompted to do (or, more accurately, "try to do") a factory restart of my Sense. But upon attempting the restart...
... "Let the LOOPING begin!"
Looking through the related Fitbit community posts, it seems that most people just gave up. Others claim to have found the "solution" to the problem, and were able to get their Senses to restart (i.e., to break out of the reboot loop).
Having tried the sequences of steps in every "solution" I could find (exactly as explained by their authors), it donned on me that, since all of the sequences were similar, but not identical, there must be an element of randomness to the "process."
So, I set about performing the steps that were common to all of the "solutions," and watched for differences in the reboot loop behavior. And then, suddenly, the face of my Sense went completely black. Then, after a short while, the Fitbit logo appeared and remained on the screen for about 30 seconds. After this, the big red X that many users described appeared on the screen, along with a warning of some sort (data sync, maybe), and then finally, my Sense launched into a normal sequence of instructions (both on the Fitbit screen and through the Fitbit app—including a software update that requires at least 25% battery power to initiate) which eventually restored my Sense to its "senses."
And that's my story!
THE END (I hope.)
