Screen does not turn ON Inspiron 15 5568 2-in-1

Hi,

I got a Dell Inspiron 15 5568 2-in-1 purchased one month ago and suddently its screen does not turn on neither after loading Windows nor before loading BIOS. I can only use my laptop by connecting an external HDMI screen.

In the Windows Video Configuration I can only choose the external HDMI screen.

I have updated BIOS and video drivers to the latest versions, but the issue persists. All the hardware tests from Dell software are OK, but it is like the screen of the laptop dissapeared,

What else can I do?

Thanks a lot for you help..