From what I've read (sorry, I don't remember where) and from studying my X3's disk drive, you could replace it with a low cost PC disk drive... But a special connector should be built for it: My X3 drive has one flat cable for both signals and power feeding.
LCD backlight is limited to some thousand hours, and it could well be that its lifetime has passed. If you are not afraid of opening your i3 , unscrewing and unplugging, you could change it yourself (I speak again from my experience with the X3, but I don't think it should differ very much from your i3).
I hope it helped...
you can e-mail me at: robertico at europe dot com.