I have a RPI 3 with a 7" touchscreen display. I encountered this issue and did some research about it but didnt find a answer. When you shutdown the OS the display goes white, then it turns black * but with the backlight on * and shows a few white lines across the display. I must mention that i used Raspbian OS the first time and I didnt have that problem.
If this helps : From another experience with the touchscreen displays ( this one was a 5" display with HDMI connection to RPI3 ) and kodi, the display has the same problem if you run kodi with the default audio settings * audio output from HDMI and ANALOG. If you want it to run correctly you must select audio output : analog. Then the display shows the correct image.
I added a few photos of the display after the shutdown
I found this info on the web, but when i go to that path i didn`t find the backlight folder and all the subfolders.
i downloaded/installed the latest version of OSMC from the website. Here is a print Screen of the folders inside sys/class
First of all thank you very much for trying to help me!!!
I tried to make this changes but i don`t have the folders you mention.
In /usr/lib/systemd/ there is no system-shutdown folder. - so i created the folder and the file with the info you gave me.
I followed your instructions step by step but sadly the result is the same. There is no difference in the shutdown process