The back light or the inverter may have gone. Press the Fn button with the F8 key and see if the screen lightens.
If this is a no,
Shine a torch onto the screen and see if you can see a dim display.
Or connect an external monitor to the vga or svideo outlet at the rear. If the screen boots on the monitor it looks like a backlight fault.
If it is this, hopefully it is still under warranty as it is a newish model.