Setting the new replacement earbud 1st gen with your another 1st earphone gen and charging case:
1. Open the Bluetoth list on your Phone and ignore the previous paired.
2. Charge the new replacement earbud with your another earphone case gen together in the charging case through charging cable for 1 to 2 hours to balance the firmware of them.
3. Open the charging case and put it close to your Phone, press the “Set” button till the white indicator light flash slowly and then the Phone will shows the new earphone.
4. Tap the screen and connect them with your phone.