The phone you bought might have problems with the Power button or battery. I recommend that you urgently get another phone through warranty. If the phone is not working at all, they should replace it as soon as possible. Alternatively, plug-out the battery and leave it like this for 30 minutes, then use another charger or connect the phone to the PC, because it should also charge it, at a slower rate through.
There isn't anything you can really do in these situations.