@KrisCVT
I think you partially answered your own question.
The bird damaged herself trying to get back to an empty nest. It is hormones talking, not thought.
In my experience, a broody hen with nothing to hatch will sit on the nest day and night for weeks, even more than the 21 days it takes to hatch chicks. They won't voluntarily come off to eat or drink. You can throw them out and they will eat a little, drink a little then start with the "broody cluck" and race right back to the box. They will "happily" starve themselves NOT hatching a darned thing if you don't throw them out. Some people think it is cruel to cage a broody to break her but I think the opposite. It is cruel to let them sit for weeks for no purpose, not eating enough or drinking enough for their needs. Now, if you have a broody and get some chicks, you can have the broody raise them. Then the broodiness serves a purpose. The "hatching" hormones drop when the chicks "hatch" or the hen can't stay hot. I had one that once melted not 1 but 2 freezer packs in series in the nest and was still
HOT underneath. If they stay in the nest the hormones won't subside.
If you make a wire cage (mine is 1/2" hardware cloth on all sides, top and bottom) and have it off the ground, the hen can't stay hot underneath and the hormones will subside. Yes they will be fussy when you first put them in but when they see the food and water, they will make use of them. And yes they will pace back and forth doing the broody cluck. But they are safe and have food and water they will eat and drink because they are NOT on a nest. My girls, depending on how long I've waited to see if they are broody or working on an egg (since that can take hours), breaking takes 3 to 5 days and they likely won't lay an egg for about 5 to 7 days after they break. My regular broodies know where they are going when I approach the nest and will scream at me.
A typical BROODING hen (according to someone I know who has had hens hatching chicks for years) will glue to the nest for ~3 days when she decides she has a big enough clutch, then will get off daily to eat, drink, poop, then go back to the nest. The last 3 days are the same as the first 3, glued to the nest. That is the difference between a hen hatching eggs and one that has nothing to hatch; the former takes care of her needs, the latter will not.