I can't be sure without being able to test it but it sounds like you have a problem with the bottom screen that is causing the top screen to not turn on all the way.
The good news is that the bottom screen is much easier to replace than the top. The bad news is that I think you probably will need to replace the bottom screen. If I would you I would get a bottom LCD that comes with the digitizer too. Since you already have it apart (assuming that you do this yourself) you might as well replace them both.
I hope this helps.