Original post by: David Roman ,
I know this thread is old, but maybe my reply could still help someone, so I am adding it. In my case, the upper right corner was dark after doing a screen replacement, and was due to missing electrical tape over 2 sets of soldered connections on the new screen. In my case, the new screen displayed properly until i closed it down into the casing, and would display properly again when I reopened the phone. I suspected crimped cables, but ultimately was able to rule it out and also rule out some other issues using my old screen (which functioned but had a dead band for touch). Ultimately, I disassembled the new screen again and compared closely with the old, which is when I found the missing electrical tape. I guess this was causing a short but only once the screen was compressed by installing it into the rear casing. Transferring the two pieces of electrical tape solved the issue for me.