Problem with Aspire 5742 LED screen unreliable

So I successfully obtained and installed a new LCD/LED panel for this laptop's screen, but it's not working relialbly. Firstly, one color (green) is missing. Secondly, the display does not always work and/or flickers and thirdly, there is a thin white line running from top to bottom of the screen. I know that the graphics card is (was) good, since the display still works when connected to an external monitor.

Does anyone have any suggestions on resolving this? I am working on the laptop for an aquantance, don't want to throw good money after bad and am quite frustrated by all of this. Any good ideas would be appreciated.