One plus 5 display(LCD light) fault. Do you have any solution?

When I was working with my One Plus 5 suddenly the screen became dark. I restarted many times but nothing has been changed.

- Power key and other function works correctly.

- touch screen works correctly.

- all sensor works correctly.

-the screen is dark even at startup there is no Logo and other image.

In these case I am sure the LCD Light has problem.

Kindly show me how can I repair the LCD Light on my One Plus 5 .