In order to hard reset a O2 XDA Guide, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
O2 XDA Guide device will be brought back to the default configuration of a brand new device.
1. Press and hold the Power button until the phone turns off.
2. Now press and hold Volume Down. Power and Enter buttons.
3. Press Volume Up to confirm the hard reset operation. Done!