Trouble with Broodies is you don't know how long they will keep going ArosP. They will stop laying and stop eating and will wear themselves out potentially -140 days is the longest I've heard of. Occupying a nest box is a problem as it upsets all the others and they can stop laying.
She needs to be moved into a dog cage on her own (but in sight of the others to retain flock membership) with enough room to get up and move about, drink and eat. You need to make sure she does. At night she can stay in the cage if she is secure enough and dry, otherwise she can go back into the coop but block all the nest boxes up. Quickest result will be had if the base of the cage is without a tray, but with mesh fine enough so her feet don't fall through. This allows air underneath her so she can't build up to the incubation temperature. She will then get fed up and stop -some in a day , some in a month. You can tell when she stands up all the time, her eyes are focussing properly and not 'glazed' and doesn't make broody noises or fluff-up her feathers. She can then go back to the coop full time and will restart laying about 2 weeks later. Word of warning -if you put her back too soon and she hasn't really 'broken' it is back to square one and start all over again. So if in doubt give her an extra day.