I went to use it yesterday to call someone and it just cut off by itself...then it restarted and it won't come back on it will just go to the startup screen where it displays the phone model and name and then the Sprint logo screen will appear, then the phone will cut off and restart, doing the same thing over and over until the battery runs dead. It's only April and I just purchased this phone in December with a new Sprint contract. What could possibly be wrong?