iPad 2 screen not working after repair

I replaced the battery in an iPad 2, and because I broke the power button cable in the process, that too. The screen worked fine after the button cable replacement, but I didn't plug the cable into the board right so they didn't work. I took the iPad back apart and re-seated the cable. Now the screen doesn't work. My computer recognizes it just fine. I checked both ends of the screen's cable to make sure they weren't damaged and that they were seated properly. Is it possible that the problem is with the lid sensor? How might I check or troubleshoot?