The iPad in my experience is very picky about what cables it will restore with. Error 9 is almost always related to the cable, NOT the dock connector/flex cable. Use the official Apple cable if you still have it, or borrow one from a friend. If that doesn't work, it might also have something to do with the IPSW you are trying to restore with. Try using a different IPSW or using Redsn0w to boot Pwned DFU mode and restore it like that. Error 9 can be related to the RAM disk kernel rejecting the ASR because it is not signed properly, thus breaking the connection with the device and causing error 9.
It definitely sounds like the LCD connector has loosened, you can try to disassemble the camera and reseat it however be VERY careful of the flash capacitor. It holds a very high voltage and can give you a nasty shock if you touch it, so make sure to discharge it first! Failing that, it is probably a failed LCD. If even replacing the LCD doesn't work, it's probably a motherboard problem, which is going to be more expensive to repair than the camera is worth.
The steps are almost exactly the same though - I've performed them on my own T420. This guide is for the T420s. Just remove the memory panel with the single screw on the base of the laptop, remove the screw with the keyboard emblem next to it, and follow the keyboard removal steps in this guide.
