You don't say how old it is, but there are a couple of possibilities. If the backlight has failed, you can usually faintly make out the screen image using a strong light. In which case the wires powering the backlight may have chafed and failed in the hinge. Or the inverter has failed. These items are replaceable, usually, but it can be complex job.
Another cable carries the image data. This also passes through the hinge and may also have chafed and failed. Again usually a replaceable part.
Graphics card failures are not unheard of, there were a spate of laptops (not only Mac I might add) that were fitted with a flawed Nvidia GPU chip, that got so hot they desoldered themselves from the circuit board. This usually requires a logic board replacement. If this is the fault, some people have successfully resurrected machines by masking off everything on the logic board bar the GPU with baking foil, and heating the GPU up with a heat gun to reflow the solder.
The best check here is to attach an external monitor and see if that works. If it does, the GPU overheat problem is not likely to be the cause, and the cable or backlight options might be worth looking into.