Samsung Galaxy Alpha - Manual (Page 15)

Getting started
15
Turning the device on and off
Press and hold the Power button for a few seconds to turn on the device.
When you turn on your device for the first time or after performing a data reset, follow the
on-screen instructions to set up your device.
To turn off the device, press and hold the Power button, and then tap Power off.
Follow all posted warnings and directions from authorized personnel in areas where
the use of wireless devices is restricted, such as airplanes and hospitals.