I just had the same problem, I don't think it's an issue with the screens, I think it's an issue with the video card or something.. I had bad digitizer, I first replaced just the digitizer as my LCD was fine, new digitizer had dead spot and I accidentally poked a hole in LCD. Had the black oooozz all over, but still worked and could see what you're doing, do I bought a assembled LCD, digitizer, and glass.. Replaced it and got a bunch of colored dots, put old screen back on, and it's now showing bunch of dots. I did notice I'm missing a pin on the phone's connector for LCD, not sure if it broke out when disconnecting old LCD or if it's supposed to be missing.
Did anyone get theirs fixed with me LCD or is the problem else where?
I noticed the internals were very similar to nexus 5, do they use same LCD or she connector, anything compatible there? I bent, wiggled, cracked old LCD and it still worked besides the black ooz, until I connected new assembly, so I'm thinking these LCD's are pretty durable and pressure on them didn't cause this issue.
Edit... Just looked up photo of connector, all pins are there.. Mine is missing 5th pin in from the right.. On bottom row..
I found the missing pin on my table, tiny thing, inserted it to connector, tossed a tad of silver solder on it,reconnected LCD ,works flawless!