A couple of days ago I accidentally removed broken links in the Core database of a new Sitecore instance using the Remove Broken Links tool at http://{your-sitecore-host}/sitecore/admin/RemoveBrokenLinks.aspx. The next time I logged into Sitecore, I got the following exception:

The model item passed into the dictionary is of type ‘Sitecore.Mvc.Presentation.RenderingModel‘, but this dictionary requires a model item of type ‘Sitecore.ExperienceAnalytics.Client.Mvc.Presentation.ExperienceAnalyticsLineChartViewModel‘.

After some digging around I found that the Remove Broken Links tool erroneously deleted the Model property of the ExperienceAnalyticsLineChart rendering in the Core database. Fortunately, the fix is easy:

1. Navigate to the Core database in the Content Editor of your Sitecore instance at http://{your-sitecore-url}/sitecore/shell/default.aspx?sc_content=core.
2. Navigate to the ExperienceAnalyticsLineChart rendering in the item tree at /sitecore/client/Applications/ExperienceAnalytics/Common/Layouts/Renderings/ExperienceAnalyticsLineChart.
3. Set the Model field to Sitecore.ExperienceAnalytics.Client.Mvc.Presentation.ExperienceAnalyticsLineChartViewModel, Sitecore.ExperienceAnalytics.Client.
4. Save the item and click OK if prompted that the item contains broken links.
5. Log back into Sitecore and the Launchpad will load.

Let me know if this helped you in the comments!