I have this Lenovo Thinkpad T440p that I just purchased used today (for parts or repair). It boots to a completely black screen, but I can very faintly see the Windows screen if I point a flash light at it. Also, the mouse pad does not work, but the right and left clicker (on the built in mouse pad) work just fine. Does anyone here have any experience with repairing the Lenovo Thinkpad T440p? I am thinking that the LCD screen needs a new back light, but is there a back light part for the screen, or does the entire screen need to be replaced? I have a Lenovo Thinkpad T420 with almost an identical LCD screen, but the only difference that I could see is the pins (the T420 uses 30 pins, and the T440p uses 40 pins, if I remember correctly). Other then the amount of pins, the 2 screens look to be identical. Would I be able to use the back light from the T420 LED LCD screen on the T440p LED LCD screen, or are they different types of back lights? Also, what could possibly cause the mouse pad to not work (when the right and left click buttons work just fine)? Thank you very much for any help with these 2 issues.