Sounds like you created a short and the back light fuse is blown. To double check take a flash light and hold it a steep angle to the face of the display do you see the faint outline of your desktop icons? If you do your in luck, if not sorry to say you have a bigger problem.
Are you able to solder very small chips? You'll need to desolder and re-solder the fuse. Are you up to this or do you think it's time to bring it in to someone who has the skills and the right gear?
Let us know what you find and your direction moving forward.