If your Fitbit device has one of the following problems, it may be fixed by a restart:
Not syncing
Not responding to button presses, taps, or swipes
Charged but doesn't turn on
Not tracking your steps or other stats
To restart your tracker:
Plug your charging cable into the USB port and insert the other end into the port on the back of your Fitbit Charge HR™. Your Charge HR will begin charging.
Press and hold the button for 10 to 12 seconds until you see the Fitbit icon and a version number (e.g. "V122").
Let go of the button.
Unplug your tracker from the charging cable.