No Backlight; replaced screen

MacBook Pro 17 A1212 (2.33 Core 2 Duo)

This MBP17 had display issues and under AppleCare I had the screen and logic board replaced twice. Now after the AppleCare is over and the 90 day warranty on those repairs is out of date, the backlight has gone out. I can see the image of the log in screen. I removed the entire display assembly and replaced with a A1151 display assembly but same results...no backlight. My guess is that this since the inverter is inside the display assembly that the issue lies in the logic board...can anyone confirm this? Not sure if this is related but the backlight on the keyboard still works.