@samt1 the bluish lines tint is most likely proof that the backlight still works. I would suggest you start by connecting an external monitor and see what that will display. If it displays properly you are most likely having issues with your screen and a replacement should resolve this problem. You should also check the wiring going to the display.
If an external monitor does not display anything you have issues with the GPU circuitry on your motherboard. That repair would most likely require a new motherboard, unless one can find the schematic to your motherboard to troubleshoot the components.