Switch it ON in the following way:
1) Press the power button for 3 seconds. A green LED will flash in the front of the device.
2) Release the button. After that, a green LED will flash every 10th second as long as it is on.
To switch it OFF, repeat the exact same thing. Press the power button for about 3 seconds and a red LED will appear. Release the button.
Important: remember to take the tracker outside before switching it ON in order to get a GPS signal faster.