If for some strange reason your headphones have become unpaired from each other, here's how to pair them again.
- On your mobile: Delete previous pairings from; Settings -> Bluetooth --> (delete, forget...)
- Put the earphones back in the case.
- On your mobile: Turn off Bluetooth.
- While holding both earphones in the case, press and hold the physical button on the charging case for 5 seconds on both earbuds simultaneously.
- Check the LEDs on the earphones, they will blink green 3 times. This means they have been reset.