In order to hard reset a Sonim XP3 Sentinel, you should perform the following steps.

Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Sonim XP3 Sentinel device will be brought back to the default configuration of a brand new device.


1. Power up the phone.

2. Go to Menu > Settings > Restore factory settings. 
3. Type in the phone's password, 0000 by default.
4. Now just allow the phone to reset'n'restart. Done!