Where the volume of friends does not check the power, the power is low, and the charging indicator will light up to remind you to charge. The key on the top of the stylus is "On". If you press "power on" for 3 seconds, a blue light will appear and a sound of "Welcome to the world of audio books" will be issued. By default, it is system a. If you press "power on" for a short time, you can switch to system B. For friends who don't use the volume stylus, Chang 'an will "power on" for 3 seconds, and the stylus will sound "Come back next time, bye-bye" and then turn it off. If you forget to turn it off, it doesn't matter. If you stand by for more than 5 minutes, the friend of the volume stylus will automatically enter the shutdown mode to protect the battery power and prolong the service life as much as possible. The battery part has safety protection such as overcharge, overcurrent and short circuit.