So I've always been told that 99% of the time, a dead backlight in an Apple laptop means it needs a new inverter board. And the few times in the past that I've had this problem, replacing the inverter board worked. But recently, about 6 months apart, the same customer had two different computers (TiBook and G4iBook) with dead backlights. I replaced the inverter board in both but neither worked afterwards. How likely is it for the actual light inside the LCD to fail? I thought this was a very rare event?