I don't think that it is anything you did, sometimes birds do get sick and die. In the future, if a bird gets sick, get her out of your coop/run and away from your other birds, hopefully to prevent the spreading to the other birds.
Sometimes birds just die. I think you did fine. I would not use any cleaner other than a broom.
Mrs K
Sometimes birds just die. I think you did fine. I would not use any cleaner other than a broom.
Mrs K