Hello

According to the product description:

"Barbapapa further has a timer that is switched on at the factory. When the timer is on, this is indicated by a small blue LED. The lamp lights up with the timer for one hour and then switches off automatically. The timer can be deactivated or reactivated by pressing and holding the on/off switch at the bottom of the lamp. When using the timer function, the time until the next recharge is significantly extended."

Greetings

Exactly as mentioned above, just press the power button for a long time until the blue LED goes out, then it burns until the battery can't anymore.