The initial comments you received were all based on your descriptions, without photos. That was a mistake, at least on my part. I can only speak for myself when I say that, once I saw the photos, it became clear that there probably was little or nothing wrong with the pistol, in the first place. Next time, I'll be sure to dig a bit deeper, before assuming that someone's descriptions are well founded.
Regardless, I hope you enjoy your M&P. Good shooting.