Tools to use SQL Server is down
The BrentOzar team's new PowerBI dashboard functionality for the First Responder kit is pretty awesome.  I use it every day to monitor/diagnose issues and it's super popular as an iPad/Surface dashboard.
https://www.brentozar.com/first-aid/first-responder-kit-power-bi-dashboard/

**I should elaborate that I use their tools to gather data from many different servers into one central reporting server, and that's the one that runs the PowerBI Dashboard.  So I can monitor all of my servers at once and from the same dashboard using these features.  This means that if the offending server crashes, I can still monitor all details until (at most 15 minutes) right before it crashed.

Other than that, I've found Dell/Quest's Spotlight on SQL Server useful too.
https://www.quest.com/products/spotlight-on-sql-server-enterprise/