Sorry to hear about the problem with your phone. You don't need to make another trip to a store. Make it easier on yourself and call customer service at 800-922-0204 for technical support. Make sure you call from a different phone and have your phone with you, otherwise they won't be able to help you. They'll troubleshoot the problem the best they can. It sounds like, however, they will need to send you a Certified Like New phone. One will be rushed to you by FedEx, usually overnighted at no charge. These phones carry the balance of the manufacturer's one year warranty or 90 days, whichever is greater.
Should you decide to cancel the line before the contract, there will be a pro-rated ETF charge assessed on the bill. The account owner will not be assessed any negative charge on their credit report, unless they let their account become delinquent. Only the account owner is able to cancel a line.
Good advice cstraight001!