How come my phone keeps shutting off?

Every time my phone is in resting mode (screen timeout mode) and it goes off but then when I try to press the button to turn it back on it doesn't turn on, it shuts completely off then I have to take my battery out to turn it back on again. What do I do whats the problem??

Hi, does the phone turn off when you are using it? it could be a problem with the phone / battery. My wife had a Note 3 and whenever she would put down her phone, the battery would slightly slip out, causing the phone to shut down.