How can I convince the Apple Store to exchange my iPhone for a new one because of a defect?
Go the the checkout counter/genius bar and tell them that you want it fixed. If they don’t give you a new one and tell you its within specs (it actually is), then go ahead and whip out your receipt and say “yeah…i want to return this”. Have the box, packaging and all materials with you…along with your sim card OUT of the iphone”. You’ll leave the store one way or another with a new phone; the only difference is how long they take to help you out.
note: I used a similar approach when getting a window replaced in my house, after the original window and the replacement window both had a scratch inside the dual-pane glass, near the center. Only there was no 30-day return option, just a lifetime warranty and words to the effect of “you know, I just bought 25 windows from you. The only reason I notice the flaw in this window is because it’s a prominent window in my living room, and you can’t miss it. There are flaws in some of my other windows, but I don’t see them every time I walk in my house so it’s easy to overlook. This window, however, is not only the most prominent in my home, but it’s also a fixed window, so it’s one of the cheapest I bought.