How do I connect a device with Xiaomi Buds 3 such as a mobile phone?

For Xiaomi Buds 3, the connection steps are as follows.
1. Connect a new device:
①Place the headset into the charging case, open the cover and press and hold the function button for 2 seconds, the indicator light of the charging case will go into white blinking state, and the headset will wait for connecting (1 minute without connecting the headset will go into hibernation and the indicator light will turn off).
Turn on Bluetooth on your mobile phone, search for and connect to "Xiaomi Buds 3". (If you need the connection password, enter "0000").
Tip 1: If the connection fails, put the headset back to the charging case and repeat the above operation.
Tip 2: For first time use, you need to activate the headset, there are 2 ways (a and b):
a. Manual power on: Make sure the headset is in the charging case and press and hold the function button for 5 seconds to activate the headset. After activation, the headset will automatically enter the wait for connection state.
b. Plug in and switch on: If the headset is in the charging case, connect the charging case to the power supply to activate the headset. (At this time, the indicator light of the charging case will be on and the headset will enter the charging state).
2. Use Xiaomi mobile phone quick connection to put the headset into the charging box, close the lid and close to the unlocked and has turned on the Bluetooth function of the Xiaomi mobile phone, open the lid of the charging box, according to the mobile phone interface prompts to connect the headset.
Tip: Quick connection function, you need to first update the mobile phone system to the latest stable version, and then open the mobile phone Bluetooth "advanced settings" open "Quick Pairing". At present, only some Xiaomi mobile phones support MIUI Pop-up quick connection.
3. Connection interruption
When the device turns off the Bluetooth or out of the range of the headset connection, Bluetooth disconnection, the headset will emit a disconnection tone, and then automatically enter the waiting for connection state; if you do not connect to any device within 5 minutes, the headset will enter the passive back to the connection state, and then enter the hibernation state after 10 minutes, and then can be awakened by wearing the headset again, and then enter the waiting for connection state.
Tip: passive back to connect means that the headset can not actively connect back to the device, you need to enter the device Bluetooth interface to manually click on the headset Bluetooth device name will be connected back. (The headset has a connection record with the device)
4. Automatic reconnection
The headset is in the charging case, open the charging case, the headset will automatically connect back to the most recently connected Bluetooth device; if no connection record is detected or cannot successfully connect back to any Bluetooth device, the headset will automatically enter the wait for connection state.
Tip: If the headset can't connect back to the device automatically, you need to connect manually in the Bluetooth interface of the device.