1， How to reset if the speaker doesn't work？
If the speaker doesn't work（For example， you can not turn off the device or no button works）， please charge it with USB cable until the LED indicator stay RED. Then remove the USB cable and power on again.
2, The speaker can not read micro SD card.
Please check the audio source format is MP3 or WAV. Size of micro SD card is same as those used on phones.
3, The max storage capacity of micro SD card WP400 support is 32GB.