0. Sign in to your Xiaomi account.

• For this, go to Settings →
• Mi Account
• Link your phone number to your account (It's necessary)

1. The first step is to enable OEM Unlocking and USB debugging on the Xiaomi phone.

• For this, go to Settings →
• About Phone →
• Then Tap MIUI version 5-7 times to enable Developer Options.
• Next go Settings →
• Additional settings →
• Developer Option.
• Then Turn on the toggle button OEM Unlocking and USB debugging options.

2. Then Turn on your mobile data and Turn off all Wifi, Hotspot and Bluetooth.

• Keep in mind, you have to turn on mobile data from the same SIM from which you have created your Mi account.

3. Now you have to Tap on Mi Unlock status.

• And then tap on the Agree button.

4. After that, you have to tap on “Add Account and Device“.

• Make sure that you have a balance on your SIM. and avoid warning message on your screen.

You should receive a confirmation that the Device was added to you account.

5. Reboot to Fastboot.

• With the device powered off, hold Volume Down + Power. Keep holding both buttons until the word “FASTBOOT” appears on the screen, then release. (For some devices there may be a different combination)

Now you can use XiaoMiToolV2 (or other unlocking tools) to proceed with the unlocking.