If your speaker has become unresponsive, please do the following:
(i) Ensure the speaker is in the full open state and not in Mic Drop mode.
(ii) Connect the USB cable and check the speaker is charging or receiving power.
(ii) Disconnect the USB cable, close the speaker to turn off, then after 1-minute try turning the speaker back on.
Should the issue persist, you may need to reboot the speaker. For full instructions on this, please refer to the Reboot speaker section in the Full User Guide.