Have I done everything to break a broody

The only way i have ever had work is completely isolate her from the nest, either lock her up or lock the nest up. If you she keeps getting access she won't stop until something hatches, she dies, or gives up after months.

Being isolated from the nest she will stop anywhere from a day later to a week at most by my experience.

 

I had a broody sumatra all summer. I let her hatch 9 chicks in the spring. As soon as they left her side she was broody again. I didn't let her have any eggs this time, but the others would kick her off the nest to lay their eggs. She kept everything warm and safe until I collected them. I tried carrying her around with me, closing her out of the coop, etc. Nothing worked. Then I decided to move the nest boxes to make more space. She didn't like that one bit and hasn't been broody since.

 

While caging is probably the best solution, I didn't have that option readily available. So I kept my broody out of the coop/pen all day. A couple hours won't do it. From dawn to dusk she was in the yard (with access to food and water) by herself. At night she was back in the coop, but I covered up the nesting box. It took only two full days, and the broodiness was broken. Good luck.