I searched Baidu for a long time but could not find a solution to this problem. Today, I have researched it myself and shared it with everyone. First connect Bluetooth according to the order in the picture: click on the English word Add below (some people ask how to press it, and it is not a touch screen. There is a horizontal bar-like button below corresponding to the one above Add). Then search for Bluetooth on the mobile phone. The name is generally called SYNC connects successfully according to the steps. The second step is the key. Many people reported that there is no sound when playing music on their mobile phone after connecting to Bluetooth. There is a row of buttons on the left, one of which says Media. Press this button until there is sound when playing. My literary talent is not good and my expressive ability is not strong. I can only explain it so far. I hope it can help friends in need.