To turn on the travel lock:
Press and hold the power button for 3 seconds. You will see the 3 charging lights light up one after the other. The travel lock light will turn solid for a moment, then start flashing as the shaver turns off. If you try to turn the shaver on, the travel lock light will flash to show the shaver is locked.
To turn off the travel lock:
Press and hold the power button again for 3 seconds. The 3 charging lights will light up one after the other. The travel lock light will quickly turn solid white, then the shaver will turn on.