Turn on
Click the power button once. You will feel a short vibration, and the device will have a blinking blue light.
Turn off
Hold down the power button for a few seconds, until you feel a short vibration.
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MORE USEFUL POWER BUTTON FUNCTIONS
Calibration
When the device is on your back and turned on, stay upright and double click the power button.
Turning the vibration feedback on/off
After the device is calibrated, click the power button once to switch between vibration on and vibration off.