Dead chicken found yesterday. Questions from the experts

[karlamaria]

She was our broody hen, constantly broody all year round except a few months in winter, and she was found dead in the coop yesterday. She has been in the best of health, eats well and seemed in perfect health . But yesterday we found her in the coop on the floor.
She seemed to want to go broody again already, last set of chicks was in September. She would have been 2 years old in March so here is what I'm thinking..
1. Egg bound though I did not see this
2. Broken egg inside her, tough again no tell tale signs.
3. Fatty liver disease. ( she eats more then the others and was firstvtovthe dish every day)
4. Her time to pass?

The other girls would not go into the coop last night, we had to force them to go to bed. Very unusual . There coop is double insulated, they have a real nice covered pen ( see pics) the coop is very big for only ten chickens so lots of room for everyone. 8x10 coop)
I purchased her from murdocks so yep she was a production bird. I'm very curious so anyone with some ideas and answers?
Her bum was clean, no mess or signs of eggs or poo, she was eating yesterday etc. I can guess that maybe she fell, but she was not under a roost.

 

[sourland]

Did you check her carefully for any sign of predation? There was some reason the other birds did not want to enter the coop.

 

[karlamaria]

Did you check her carefully for any sign of predation?  There was some reason the other birds did not want to enter the coop.

. Not possible. I have a totally I closed pen, and top, live in a back yard, and no signs of digging or invader.

 

[karlamaria]

No marks on her, no blood no signs of trauma .