I bought my 9550 (i5/4k/256gb/8gb) on Feb 6 from the Microsoft Store. It suffered from some black screen issues, even after updating everything fully, BIOS, Intel/Nvidia drivers etc.
The past week, a new development has occurred. The laptop goes to black screen and a loud buzzing noise emits from the speakers. It's not the usual coil whine but a really loud buzzing sound. This happened once when I was watching a short video on Facebook, and again when I was watching a video on Youtube, both times using the laptop's speakers. It has crashed to a black screen before while watching YT but without the buzzing noise (I was using headphones), this is new. I have checked that everything has been updated, and it has, yet this is happening.
I'm past my return date, and surely all the force shut-downs I have to do because of the black screen can't be good for the laptop. I hate that I can't even watch a video without fear of my laptop black screening and making me force reboot. Why should I have anxiety over using something I just bought and paid so much for! Really frustrating laptop. Just another problem on top of all the others it has had.
Same thing is happening to me. I'm so paranoid about losing documents now that I save every few minutes as I'm constantly having to re-write lost work...and like you say, I can't relax to watch a video or movie because of this problem. Really disappointed.