The waranty issue is correct. Since you are not the original purchaser of teh phone, there is no record of your ownership, therefore, you get no warranty. However, as you were told by the rep, if you produce the original receipt, you will be covered by the warranty. Generally speaking, the manufacturer's warranty is transferable, with proof of ownership.
As for your particular troubleshooting issue, there could be numerous things wrong, from a defective phone to a failed activation.