My Grandma has an iPad Mini that's in great condition she never used it that much so she gave it to me. The issue is it's in activation lock. She doesn't remember the password to her apple id as well as the password to her yahoo mail, to change her password I would need to enter the digits to her phone number that cant be accessed. I managed to factory reset the iPad, but it's still under activation lock with her apple id. What do I do to unlock the activation lock?