I had exactly the same problem. I did extensive testing and found that the display would light up but no video was displayed. I found that the chips on the right connector at the bottom of the LCD orange connector protruded more than the original screen. The metal cage that holds the screen connectors down, shorts out the chips. If you removed the metal cage, the screen will display. I used some tape on the metal cage to stop the short. For more info contact me through JP Computers

This is not always the case. The Corona version of the motherboard has an integrated NAND chip that cannot be removed without specialist soldering equipment. The earlier versions of the Slim do indeed have a sisterboard that can be pulled away from the socket. http://www.jpcomputers.co.uk