Dude(and everyone with the same problem) the same happened to me, in fact the image was normal at the beginning, 2 min after "poof" color lines everywhere. In my case I suppose my new LCD screen is faulty since I have pride and can´t admit I did the assembly in the wrong way.
To any of you who are desperate, you should be, I still didn't fix the problem, but the best course of action that I thought for me and you after searching forums, bla,bla, etc... is:
Ordering a new screen and BENCH test it(like assortedrubbish said), this will allow you to know 100% at the beginning if the screen is good, and after the assembly if it's bad you will know 100% that you fuc*** up. To bench test it, what you have to do is simple, only take out the rear case> disconnect the battery>disconnect the display screen cables>connect the cables from the new display screen>connect the battery>and check if the new screen display is good. If it's good, do the full display assembly with the new screen, and at the end if the screen doesn't work it's because you made some mistake.
Note: What everyone concludes when this happens is that the new screen is bad, but in reality there is two conclusions the screen is bad or it was human error which is perfectly normal cause the display can be ruined just by bending the display cables a little too much.
I just feel sorry that I didn't even thought of bench testing the screen first, cause now I will have to waste the same amount of time when assembling a new screen again...