After the earbuds has been connected to the mobile phone, what should I do if it does not automatically reconnect after opening the case?

Please refer to the following.
1. The earbuds automatically reconnects to the last connected device by default. If the last connection is not your current phone, you need to reset the earbuds and reconnect to the phone.
2. The mobile phone is far away from the earbuds, exceeding the effective transmission distance (10m), or there is an obstacle between the earbuds and the mobile phone.
3. The Bluetooth of the mobile phone is not turned on.
4. Due to the particularity of the earbuds, the electromagnetic waves in your area may interfere with the Bluetooth connection, and the earbuds may be disconnected and cannot be automatically reconnected in time.