press and hold the power button while sliding the mute switch back and forth 3 times then retry. try pressing and holding the following keys in this order orange, sym, r then retry. if those fail you are going to need to call *2 from another Sprint phone and speak with a sprint worker. they will need to run you through an RTN process. be sure to select "yes" on the question of "was your issue resolved" if you get a survey.
Go to "Launcher>Device Info>Reset Options>Full Erase" It will reset your phone to factory settings requiring you to add the proper information to activate.
@Brian, Don't be begging for a "yes" on the surveys, If you do a good job and solve the issue we will rate you accordingly. nothing worse then speaking to a rep and they beg for a positive review to ensure they get a bonus. Being nice to the customer and doing all you can to try to solve their issue should be your only concern.