Sl510 Black screen display

@manqoba start off by checking your backlight. To check your backlight use a flashlight and shine the beam at an angle against the screen. Do that in a darkened room. See if you can make out shadows or shapes. If so, it is your backlight that has failed. either the LEDs or the backlight circuitry on your board will have to be checked.

Next attach an external monitor to your ThinkPad. IF that does not show an image as well, then the issue is most likely a bad GPU. If that shows properly you know the issue is with your LCD. Could be the display or even things like the display cable, display adapter etc. so let us know what you find out.