Replace your battery (CR2032 Lithium watch battery), following the instructions on page 10. In rare cases, an electrostatic discharge (static electricity “shock”) may cause your display’s unit to go blank. In dry weather, a charge can build up while the unit is being carried in the storage pouch or a pocket and be discharged when the unit is touched or placed on the mounting bracket. If this happens, you can perform a complete reset of your unit as follows:
Open the battery door and remove the battery. Leave the battery out for at least 10 seconds while pressing and holding the button. Release the button and reinstall the battery. The unit should turn on and function normally when you push the button.
If this procedure does not solve the problem, and your unit is more than 2 years old, try replacing the battery.