When the power is on and the blue led is on, it goes into Bluetooth mode and is ready to pair. 

The device's Bluetooth name with display as “XY_BT”.

The device will play “The Bluetooth device is connected successfully” when successfully connected.

Micro-USB or a soldered 3.7-5V connection can power the device.

Stereo audio is output either with the 3.5mm headphone jack or the soldered connection.