Hard Reset CATERPILLAR S40

First method:

1. The device must be turned off, so hold down the Power rocker for a while.
2. Afterwards press and hold the Volume Up button for a few seconds.
3. While still holding the Volume Up connect your device to PC or charger by using Micro USB cable.
4. You can release held key as soon as the Recovery Mode appears on the screen.
5. In the next step use Volume buttons to select "wipe data/factory reset" and tap the Power button to confirm.
6. Afterwards choose "yes" from the menu, and accept it with Power button.
7. After a while accept option "reboot system now" using Power rocker.
8. That's all. The hard reset operation should be completed.

Second method:

1. At the very beginning hold down the Power key for a short while in order to switch off the device.
2. In the next step go to Settings and select Backup & Reset.
3. Then tap Factory Data Reset and Reset Phone.
4. After that, choose Erase Everything if you are sure you want to clear all your data. 
5. Finally, select OK to confirm the whole operation.
6. Congratulations! Your phone is ready to use.