worth a try, don't tell em it's from ebay.
just act like you got it from them.
I activated my phone myself, and got it from over the customer service 800 number.
but they didn't even question anything about where I got it or what not,
i just said that, and they said ok and started filling out the paperwork they needed to do to log it as DOA (dead on arrival)
and then gave me a new one.