Man that's bad news !!!
Especially on brood birds and being shipped (i know it's aggravating) .... i feel for you .
Do you think she might have had a heart attack ?
Can't see her head .... any sign of fighting (or was she in with another bird ?)
I've heard of it happening but i guess i'm lucky (never had one to die) .
I had 4 roosters i shipped to N.C.(from south Alabama) to get lost for 4 days after they got to N.C. and the ole boy that gott'em said were find and they won a show a week or two later .(somebody must have fed and watered them at the terminal)this was in the 70's ...... he had found this tool delivery company that would haul chickens , dogs , anything in a crate , (that was the only problem we had with them) but those days are gone . .
And i've shipped and received in summer many times(even this year) (i always cut a cross slit in sheet that covers the air holes) i have been guilty of cutting some of it out or just glueing a piece of vinyl screen where the sheet is supposed to be .
Friend I do feel bad that you lost her (wish there was something i could do)