Unable to turn on the speaker or the speaker suddenly turns off
The rechargeable built-in battery may be empty or running low. Connect the speaker to an AC outlet with a USB AC adaptor (commercially available).
Depending on the type or specifications of the USB AC adaptor, if you use the speaker at a loud volume, the remaining power of the rechargeable built-in battery may decrease or the speaker may turn off even while the speaker is connected to an AC outlet by the USB AC adaptor. This, however, does not indicate a malfunction. If such a case occurs, turn off the speaker and let the battery fully charge itself before you use the speaker.
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.