Switch Lite starting but black screen, pic with flashlight visible

Hi all,

i got a Switch Lite which starts normal with sound and also touch ist working but the screen stays black. I took a flashlight and was able to see a picture when i shine through.

Already replaced the backlight controller and tried a different daughter board without any success. Coil and diode on the backlight circuit show 3,7v even with another display.

Any ideas what to do?