Unable to turn on the speaker or the speaker suddenly turns off
The built-in battery may be empty or running low. Charge the speaker by connecting the speaker to an AC outlet via a USB AC adaptor (commercially available), or connecting it to a booted computer.
The auto power off (Auto Standby) function may have activated. After about 15 minutes in certain circumstances, such as when the volume of the audio input is low, the power will automatically turn off. Raise the volume of the connected device for use, or set the auto power function to off.