I had the same problem i took the screen apart i have done it before on 3 other machines and have been successful but with this,still a white screen
i got a new screen and cable and it still doesent work it does through an external moniter so i dont know what the problem is just thought mac would have something to help this problem the design is so bad cbles cut by hinges why would you design it like that
i cant see any other way of fixing it even mac repairs said it would be around £300 to fix not including postage and hourly charge whats stupid easier to buy an external moniter and fit it to it