Z18 Battery died

Can I change the Battery on my Z18?
My Z18 Phone does not start. The phone just went off. I can’t say exactly why. When I looked at the phone today after an hour it was off. Even when I try a hard reset (press power button 30 sec, volume + power button) nothing happens. The first time it went into fast boot mode, now nothing happens.
I think that the battery is faulty. I just want to reboot the phone and pull some data from it.