The "Quick Test" (and Full Test) take long time and can not finish. There is a message:
Multiple instances of SupportAssist running on your machine. Please restart the service. From TaskManager, goto Services and select SupportAssistAgent. Restart SupportAssistAgent.
After Restarting SupportAssistAgent, the same error message is showing
My OS: Windows 10 Home.
Instead run diagnostics from the F12 startup option. Restart the system and at the Dell splash screen start tapping F12. Run system diagnostics from that menu. I have always preferred to run diagnostics that way rather than SA.