1. Do you see the bios splash screen ?
If the computer screen is black from the get go, i recommend using a torch and shine on the screen and see if windows is displayed as normal except for extremely dimmed/black screen, this symptom is due to the failure of the backlight of the screen. Depending on how the screen is made it should be easy enough to replace it. The backlight, especially in older laptops was called FL-INVERTER.