1) Forget the earbuds from APP

2) Now remove/forget the Bluetooth name from Mobile Phone's Bluetooth settings.

3) RESET the earbuds (case button for 15 seconds with the lid open) and then again bring it into pairing mode and now upgrade the software

4) Keep the lid open or the earbuds out of the case during the upgrade, and keep the battery above 50%.

5) Restart the mobile and try again with a stable connection, keeping the mobile next to the earbuds. If it still fails then RPU.