There are so many good tips on this subject! I am experiencing this for the first time, and so far, my girl is stubborn, trance-like and quick with the stink eye, but not psychotic. Luckily, she is laying at night or early morning, and I am able to lock her out of the coop during the day. When her sister needs to do her business, I lock her in the coop, and take Miss Broody to the back yard alone. Poor thing, though. It's kind of sad to see how determined and persistent she is to get into that coop, and the desperation when she can't find the box.
I have tried to take her out of the box and place her on her roost at night, but she just finds her way back down, over and over. I take the box out at night, so she just sleeps on the wire. Day three coming up, seems that time away from the coop is helping, but in the evening she will do ANYTHING to get back in. She even pecked my cat! Well, mainly because the cat was in the nesting box that was sitting on top of the coop. Let's just say that is no longer the nesting box hiding place...
Hope this ends soon, we don't have a rooster and babies are not in their future so I hope she'll be fairly easy to break now and every time. Oh brother! Good luck!