We started a sprint yesterday. But today there is a major change. We have moved a bunch of additional stuff into the sprint and the burndown chart looks really strange. I know the reason is that -- right or wrong -- the sprint was started when it had on 10 points. Now it has almost 90.
Is there a way to stop this sprint and restart it?
Technically speaking, you can't stop and restart, but you should be able to end the current sprint and start another. Make sure all the issues are not resolved and they should return back into your backlog. You can name it the same thing, but technically, it'll be a different sprint.
You also cannot set the Sprint start date in the past, but after you create the sprint, you are able to adjust Start Date in the Cog menu of on the Work view.