Hi,

You need to try to hard reset your phone.

Before you do, try if you can, to charge the phone battery so that it has a reasonable amount of charge.

Do not perform a hard reset with the charger connected.

Warning : A hard reset will erase all your downloaded apps and user data and will restore your phone to factory default condition.

To perform a hard reset :

Turn your phone off.

Press & hold the Volume Up and Power buttons together.

Release the Power button when the Mi logo appears on the screen (don’t release the volume up button yet).

When Recovery mode shows, release the Volume Up button

Navigate using the volume buttons (up or down) and confirm by using the power button.

Select “English” (or whatever language you prefer).

Then select “Wipe Reset”.

Next choose “Wipe all data” and confirm by selecting “Yes”.

Be patient the process takes a few minutes.