[mothered]

should I instead order the phone online and return it in store?

As with every In-store SE, attend late on a Thursday/Friday just before close of business - namely when they're Inundated with customers and returns. As such, they won't have time to thoroughly check the return.

Also, Identify the most vulnerable employee at the service counter. For example, young females tend to be naive/gullible, hence distract her by complementing her hair and nails etc. You'll find that everything mentioned, will draw attention away from the possibility of checking every part of the return.