Hey experts - I have a macbook pro I am trying to use. It hasn't been used in a long time. It's from 2011.... But I have used it in the last year because it's running the sierra beta I think. When I turn it on, it asks for my password. I enter it and it shows a loading bar. And then a box pops up asking for accountsd wants to use the "login" keychain. It won't load past this and I have tried every password I can think of and it doesn't accept any of them. So I am stuck on a grey screen with a loading bar three quarters of the way loaded and a pop up that won't go away because I don't know the password. What are my options??