[Roffey]

We were away for the night and came home to one of the BAs dead as a door nail. Looked as they she fell right off the roost. No indication of being harmed.
My other BA is super broody almost concerning. I haven’t seen her leave the egg box in days. I actually picked her up (against her will) and put her by the water.

 

[robin416]

Sudden death does happen with them. Not just the this breed but all the breeds.

All you can really do is watch the others to make sure you don't see any changes. They can be very subtle.

Is the BA setting on fertile eggs?

 

[Roffey]

No I don’t have a rooster
And she hasn’t layed for 2-3 days either

 

[robin416]

She's broody. Oh joy, you get to have one that wants to hatch eggs and raise chicks.

 

[Lillith]

Yeah, occasionally a chicken just dies. Heart attack, genetic defect, whatever, it happens sometimes. I would be more concerned if multiple chickens were dropping dead at the same time, which to me would indicate some sort of disease.

No I don’t have a rooster
And she hasn’t layed for 2-3 days either

It's normal for them not lay when they are broody. You can break her by blocking access to the nesting boxes (not always a great option if you have other chickens that need to lay, and, they usually just make a different spot!), continually removing her from her nest, picking up all eggs promptly so she has nothing to sit on, or putting her in "chicken jail", which can just be a dog crate with food and water in it.

If you want her to sit, you would have to purchase fertilized eggs and sneak them under her at night, switching the dud eggs for the fertilized. Or, you can count 21 days and sneak baby chicks purchased from a farm store or something under her, but that doesn't always work.