You are correct in return policy through AT&T. After 14 days it should be returned to Samsung. You might be able to take it to AT&T and they might ship it out for you... Big maybe.
Sent from my SAMSUNG-SM-G900A using XDA Premium 4 mobile app
SGS 5--AT&T--STOCK NO MORE! NCE EXTREME DEBLOAT!
NEXUS 5--AT&T--MULTI-ROM MYSTERY MEAT