I haven't touched a xiaomi brand.
But why you just don't ask your cousin?
Did you asked her permission to do that to her/his phone?
Already asked my cousin but she forgot what her account is and it's really frustrating.
There's nothing much that we can do with that.
All you have to do is to look for those forums that can help you with this problem. A specific forum for Xiaomi users, I think that they have it.
Search if your local has that kind of forum. I checked the official Xiaomi forum but it looks like only an update for their products.