Please follow the below steps to reset your earbuds and try repairing with your phone.
1. Remove BCS-T90 from the paired device list on the Bluetooth Setting menu of your phone
2. Remove both earbuds (L) and (R) from charging case.
3. Choose earbud(L) or (R) to initiate factory reset.
4. Cover the earbud sensor with your finger
5. Double tap the earbud and hold for 15 seconds while covering the sensor
6. Earbud LED will flash 2 times once it enters reset mode.
7. Repeat Steps 3 to 5 for the other earbud.
8. Once both earbud(L) and (R) are reset, earbuds will sync and automatically enter pairing mode. Continuous LED flash indicates that the earbuds are ready to pair.
For better visualization, please refer to the following link to view video instruction of factory reset.