We had to add an issue to our sprint. The person entering the issue mistyped and put "45" in the estimate field, meaning minutes but the system was set to default to days. This caused our burndown report to show a spike of 9 weeks scope change for the ongoing sprint, which completely flattened the useful part of the graph to a slim line at the bottom.

You can revise the estimate but the large spike still flattens the graph. We need a supported mechanism which can be used by product owners (ie not SQL experts) to edit or remove the history of a bad estimate change to restore the graph.

Mistypes happen. To have a sprint completely and utterly broken with invalid/unreadable results by a single mistype is not reasonable or expected behavior.