Did you disconnect/isolate the battery when you removed the LCD? Not doing this can cause problems with the backlight circuit (although in this case it appears the backlight works but not the "image"). It is possible the the LCD driver circuit was damaged.
I would go back through [guide|11970|the guide] and double check your steps. You may have damaged the connectors on the logic board or inadvertently pried off some surrounding components. You may also have damaged the LCD, it is quite delicate.
Take a look and get back to us with more details.