While recording an exercise you can lock the buttons by keeping the lower right button pressed. Once locked, you cannot change the display views, but you can turn on the backlight with any button press if the backlight is in automatic mode.
To unlock, keep the lower right button pressed again.
When you are not recording an exercise, the screen dims after a short period of inactivity. To activate the screen, press any button.
After a longer period of inactivity, the watch goes into hibernation mode and turns the screen off completely. Any movement reactivates the screen.