I have a 2016 MacBook Pro running Sierra and the screen has gone black. I'm using my HDTV now for an external monitor. I want to do a diagnostics test to find out what to fix. But the external monitor doesn't work when I try to run the diagnostics, so I can't see the results. Also screen sharing works but not when I try to run diagnostics. I have tried holding D key at startup and also Option-D. I have tried SNC reset, PRAM reset, booting from an external drive, all the usual. Does anyone have a workaround? Thanks!