In order to hard reset a O2 XDA Atom Exec, 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 Atom Exec device will be brought back to the default configuration of a brand new device.
1. Heyoo! Start by pressing and holding Reset and Power buttons (use stylus to press the former).
2. Unless something went wrong, your phone should now reset and restart. Done!