I have tried everything possible, that I know. The models are completely unfold able due to their high polycount. I do not have the knowledge to try to reduce the polygons and simplify them myself. But on that note, the one person I know who can, tried on another Halo 5 model for me and had no luck. You will have to find a 3d master and even then there is no guarantee. The models are just to detailed for Pepakura's capability.
Also, I recommend a heavy dose of patience and humility. Your reaction is not encouraging people to help you.