I have the same problem. Please check this video: https://www.youtube.com/watch?v=DVMsZH0D... At the top of screen is oca for iphone 6 and bottom of the screen is oca for iPhone 5. Do you have any experience with defective oca glue ? Unfortunately I don't have another pack of oca for iphone 6 so I can't test it. Is the oca for iPhone 6 defective ?
I think that you should have any experience with soldering in general. Then you need good solder with hot air. Don't try it to working motherboard. Buy some crash or locked motherboard. Everyone has to find your way. Youtube will your friend