a) Please ensure if device did not get connect to the previous input device. Ensure to forgot or remove it from there

b) Volume level need to check, and ask CX to set the desired volume level from Mobile Phone and ear buds both 

c) If using online APP then suggest cx to check internet connection

d) If using online APP, please check its compatibility with Mobile Phone and allow permissions from APP Manager in Mobile Phone

e) Mobile phone can also have issues in this case. CX can check if the device is working well with other mobile phone 

f) RESET the device

1- Remove device name from Bluetooth Interface
2- Open the charging case and let the buds stay in
3- Press and hold the reset button for 7 seconds
4- the LED on the buds will blink 5 times indicating the buds have been RESET then repeat the pairing process.