I know the answer (but probably too late). There is a small smd type fuse (F9900) on the IO board which is required to power up the backlight. It seems that in your case it got busted.
Louis,after replacing the blown left io board (the original one didn't recognize the power supply), my screen lost its backlight. so I got two broken IO boards. Could you please point to what is a driver chip and where is F9800 and the fuse? Hope I could build a working one out of these two...