How to completely reset an Android phone?

Question

Android

The story is like this. My sister's Xiaomi redmi note 4 got stuck while loading Android itself. At first I just took out the battery, stuck it in and repeated, nothing happened. Then I got into something like Recavory and reset the settings already there. It booted from the factory state BUT, when it came time to bind Gmail, IT turned out to be necessary to enter the MAIL THAT WAS ON THIS PHONE BEFORE THE RESET. No one remembers the sister's mail password, BUT there was also a dad's mail (it was his phone at first), but he moved out of the family, so it's a bummer, I know the mail itself, and he changed the password exactly 36 days ago. I tried to write to him, he refused to help. I thought I could somehow reset this lock through freeboot, but how? Please help me, how can I get rid of this limitation and RESTORE THE PHONE NORMALLY?!?!

Answer 1

If I understand correctly, this is Google Factory Reset Protection.
As planned, this is to protect devices from being used by thieves, etc.
there are ways, they google, the first result, for example

Answer 2

You can reflash smart xiaomi reflashing is not so difficult on the internet full of guides an example for this at the link https://www.youtube.com/watch?v=PVaFV46JfFE