I just fixed mine. There is nothing to do with the cable, just the LCD screen. I got a cheap used one from ebay, took out the LCD screen from it and put it back to my old one. Now, everything is working again. I put a new screen protector on it, and my N800 looks like a brand new one. I am so happy to get my N800 back, even though I have an Android Tablet and an Ipod touch 4. The N800 feels so solid in my hand.
I really hope more people can develop the programs for 2008OS, but I doubt it.