I got a xiaomi mi4i from my brother a while ago which was lying with him for quite a while. So, after I got it, I did a factory reset and tried logging into mi account only to realize that the device has been associated with another account. I asked my brother about account info but he had given the phone to a friend and he doesn't remember the account. So, basically the phone is useless right now.
BTW, before anyone of you say so, this phone is not stolen and I have the proof of purchase with me.
So, is there anything I can do to remove the associated mi account?
I know I can downgrade the OS to unlock it, but as soon as I upgrade from it, it again locks the phone with a message "this device is locked". what can I do to unlock it?