no backlight but there is sound and logo at start

Hello

I have a samsung tv model uk43k5002akxeq. When i turn it on, i see the samsung logo for less then a second then after that no image, only sound and when i point a flash light on the screen i see a dim image.

can anyone suggest me a solution, cause i dont think this a backlight issue since it works at the start when it shows the logo for less then a second