I was listening to music and texting.. like the usual, but then my cellphone just shutted off on me, and afterwards, it just would vibrate every 5 seconds. i would remove the battery and put it back on, still.. it would do the SAME THING. I tried plugging in the charger with the battery.. it would turn on to the start up page then it would shut down half way and it would STILL vibrate every 5 seconds. What's wrong with my phone? how can i fix this?