1900x1200 LCD replacement did not work?

Hi, i followed the instrutions on this guide : MacBook Pro 15" Core Duo Model A1150 LCD Panel High Definition (1920x1200) Replacement, and it did not work. On boot up, a blur image of the apple logo and spinning wheel appears and then the screen turns black. When hooked up to an external screen, I can see the desktop all loaded properly.

Any help is greatly appreciated!

Many thanks, Ben