As part of a troubleshooting experience with Microsoft Band support recently, the rep had me perform a "soft reset" of the device. I had never had to perform this before, and frankly had no idea this option existed. The reset didn't help my particularly situation, but it is handy knowledge to have.
A soft reset is a bit different than shutting down the band using the Power Button (the button in the middle of the band) or the option in the Settings tile. A soft reset forces the Microsoft Band to empty cache and potentially anything stored in memory that has become corrupted. It puts the band's memory back to a pristine state, but keeps all your personalized settings. The soft reset does not delete any customizations such as backgrounds, themes, tile arrangements, or even your recorded fitness activities and step counts for the day.
To do it…
Hold down both the Power button and the Action button for approximately 20 seconds, ignoring any prompts that might display during the procedure.
When the band shuts down and goes to a black/blank screen, the process has completed. Once the soft reset has been accomplished, you have to plug the band directly into the charging cable before it will turn on again. The soft reset makes the band "think" that the band's battery was depleted, and you will need to set the time and date again.
If you're having issues with your band, particularly connecting to the Microsoft Health app, a soft reset could get you going again.