Vostro 15 7510

Hello, I have a problem with a dark screen.
The laptop is connected to power, when the POWER button is pressed, you can see the charging LED blinking alternately white and orange. You can also see the keyboard backlight but the screen is still dark....
Connecting to an external video output via HDMI also has no effect.
The matrix can be seen to be working because the laptop goes through screen check mode, a combination of the D key and the POWER button - individual colors are displayed.

Please give me some tips on how to solve this persistent problem

Translated with  (free version)