I think that will be hard to solve without at least some photos but offhand the only way I would see the pole forming an S shape is if a shaped pole section was in the wrong order and somehow held in the wrong direction. The trouble with that is that as far as I can tell the HD2+ doesn't have shaped pole sections.
It seems likely that you have the pole sections mixed up. If it were me I would take the poles apart again and systematically re assemble them without the shock cord using the tent body as a jig to figure out how the poles are supposed to go together. If they are mostly identical then there should be only a few possible variations.
Not sure if it is useful or not but here is a photo of what I believe is the same pole set you have
and here is a fairly extensive review of the HD2+ with photos
From those you might be able to get a good idea as to how the pole sections are supposed to be assembled.