Well it is possible that the battery died, or the phone died.
If you can't get it to do anything, and the device is still under warranty, then I would contact the manufacturer about it.
If it isn't under warranty, the only option I can think of, beside replacing the battery, is to try a "Hard Reset".
NOTE: Doing this will clear 'all' the data on your phone, so it is suggested you not choose this option unless you have to, or aren't worried about losing anything on the phone.
Be sure you back up any data you want to keep, to a computer or cloud account, before doing the reset.
To "Hard Reset" the phone...
1. Make sure that the phone is actually powered off.
2. Press the "Power" and the "Volume Up" buttons, together, until you...