My LCD is not lighting up. It did before I replaced the power cable

Did you isolate the battery from the logic board before disconnecting the LCD? Not doing so can cause the backlight circuit on the logic board to blow. One way to test for this is to shine a bright flashlight on the screen when you turn it on or connect it to an iTunes enabled computer. If you see a dim image, that means the problem is with the backlight.

Double check the condition of the flex cable and connector for the LCD and if everything looks okay, then it's probably logic board related, which would require a micro-soldering repair.