Try connecting an external display to see if you can get any video to the external display. Unfortunately it can be very difficult to get video to an external display on a Mac when the internal display is non-functional. If you have issues, then try connecting the charger and a wired USB keyboard & mouse....then close the Display of the laptop & hope it will enable Clamshell mode where it will force video to the external display. Unfortunately even this is not guaranteed to work. Sometimes it is best to force the laptop to power off. Then when powering on the laptop, close the display lid immediately after the startup chime.
You can also try closing the Display lid, then very slowly & carefully just a little bit to see if you can see a video signal or backlight on the built-in display which would indicate the laptop has the known display cable flaw, but at least it would allow you to configure an external display more easily if the above did not work.