MBP 15" Screen issues

Hello all, I have a 15" Macbook Pro with a 2.0GHz Core Duo. The screen all of a sudden wouldn't turn on when it booted, but I could barely make out that it was working, but very dim. I went ahead and replaced the inverter and that did not do the trick. After that didn't work, I replaced the LCD with a glossy 15" (it was matte) and now it still does not work. It is still very dim, and you can use a flashlight to see where the mouse is. Does anyone have any ideas? The only things I thought that had to do with the screen were the LCD and inverter. All the cables look fine and the ground strap for the display cable is in good shape as well. I'm at odds here and I'm ready to trash it... Thanks for any info!

I also replaced the display cable and inverter cable. Now I'm $200 down and it still does the same thing. I'm pretty sure it's the motherboard, so I'm done with this one...