Answer to "No display backlight, no warranty, left IO board to blame, options?"If you short the fuse, you will create a fire. If you are actually an engineer, you should know better than to suggest this. Shorting fuses used to be something that you would never do under any circumstances. I see at least 3 boards per week where people tried to short fuses and it failed. I see many where they did successfully without causing fires. Please don't do this. http://www.rossmannsupply.com/blog/?p=32 Replace that component. You should be just fine. Update: edit, I did not see your response where you stated you've already found F9800. There are two ICs on the main logic board that control the backlight voltage for the left I/O board, a driver chip on the left I/O board next to F9800, and a fuse. Can you please let us know which exactly was bad on your model? Lastly, sometimes these fuses blow but still show continuity on some meters because it is not fully disconnected, just high impedance. I see this happen often. It could not be fully blown.
Answer to "No backlight display; what are possible causes"http://www.rossmannsupply.com/blog/?p=32