Usually the keyboard is held down by couple or three, even four screws from bottom (special marking besides each screw denoting them), once done, lift out the keyboard and you will see LCD cable plug, if power button is seperate from keyboard, turn on and press down on that LCD plug to see any changes.
Some did have little hooks around the edge of keyboard assembly, you have to gently ease edge of keyboard around each hook. It is just a hint of each hook.
Be certain problem is either with mainboard itself (video chipset or LCD itself. What model is this?).
Cheers, Wizard