On these, the display assembly is not repairable - it's fused together.  If the cable is damaged, the display assembly needs to be replaced. [URL]
Got no display or the screen flicking on my Dell XPS 9570 which has 4K display, here is what I did so far: 1. Connect it with the external monitor, images showing correctly on the external monitor, but not on the built-in display 2. Open the back cover and try to wiggle the video cable, or move the display with different angles on hinge, and got the image back on built-in display some times, one or two times has the image showing correctly on the built-in display for a few minutes. 3. Most of the time, has no images on the built-in display, if there is, then it is just flickering. I suspect the video cable (or the video ribbon cable) might be damaged or broken which caused the connection not stable, is there a way to replace the video cable only or have to change a new display assembly? Any thoughts? Thanks for any advise. 
How to replace video cable for Dell XPS 9570?