1. Please check whether the APP version is the latest version first?

You could download the APP from our forum or the app store: https://forum.fiio.com/note/showNoteContent.do?id=202105071628040377809&tid=17

2. If the app quit working still, it is suggested to clear the pairing record of the Bluetooth device in your phone. Then reconnect it to your phone and try again.

3. For the iOS version: the first time to enter “Bluetooth device control”, short press the power button(For Q5, please click the input button) of the Bluetooth device to finish connection, and then click “Cancel” and return to “Bluetooth device control” menu. It will be connected successfully. At this time, click Bluetooth device to execute relating operations.

4. For the iOS version: if the Bluetooth device did not show up in the “Bluetooth device control” list, click the “Refresh” icon in the upper right corner, or quit the app for a while and then reenter it.