Why is my phone vibrating all the time?

I have Samsung Galaxy Centura for 6 months, and recently started to vibrate and stopped working. I thought that the phone needs new battery, so I replaced the old one, but that did not fix the problem. Now my phone is not working at all. When I turn phone on, stay on for one minute, then vibrates and freezes. No solution. I tried to connect to the computer and at least download the pictures and music I have on, but when the phone is on, lasts only one minute and then no sign of working at all. Is there any way to fix this, or I need a new phone.
Vibrating happened before, but after I restarted the phone two three times in a row, started working normally. Now, doesn't.

Sounds as if the phone got wet. (It didn't have to fall into water or have water spilled on it. A below-freezing phone, brought into a warm house, causes condensation inside the phone, which causes water damage.) If that's the case, there's not much you can do now.