Restore broken Grafana dashboard

Hello, I misconfigured Grafana dashboard JSON and now it does not load and shows error. The problem is that I even cannot get to dashboard settings to see versions to restore previous version. How can I fix JSON in such broken dashboard?

I was very lucky I had the original dashboard running on other computer, because it is managed in the browser. I saved it under different name and then used this new name. I will never mess up with JSON configuration again!