This will help shut it down
Turn off the device.
Remove the back cover.
Remove the SIM card.
Wait several seconds then re-install the SIM card and replace the back cover.
Press and hold down the Volume up key and the Power button at the same time until a menu screen appears.
Press the Volume down button to select Recovery.
Press the Power button to select the language you would prefer.
Use the Volume down key to navigate to wipe cache partition.
Press the Power button to select this option.
Use the volume keys to navigate to Reboot system now, press the Power button to reboot the device.