Hard Reset SAMSUNG G800 Galaxy S5 mini Duos

First method:

1. Press Power button until your phone is on.
   
2. Then you should to press and hold Volume Up button + Home button + Power button.
   
3. Now if you are in Factory reset menu, then use Volume Down key to select "Wipe Data / Factory Reset" option and press Power buton to confirm the operation.
   
4. Select "Yes delete all user data".
5. Next accept option "reboot system now".
6. Finito!

Second method:

1. Switch on your device.
   
2. Next please open the dial pad on your phone and enter: *2767*3855#
3. Then you will see, that your phone will reset and reboots.
4. Well done!

Third method:

1. Turn on your cell phone.
   
2. Now if you are in the Home screen select Menu.
3. Afterwards tap Settings -> Back up and reset -> Reset device -> Delete all.
4. Accept all warnings, and wait to reboots phone.
5. Good job!

WARNING !
Hard Reset will erase all of your data
All described operations you are doing at your own risk.