In order to hard reset a Samsung Google Nexus S I9020A, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Samsung Google Nexus S I9020A device will be brought back to the default configuration of a brand new device.
1. Heyoo. Start by turning the phone off and removing its battery.
2. Now press & hold the Volume Up and Power buttons. Boot Mode menu should eventually appear onscreen.
3. From that menu, select Recovery.
4. Wait for an Android screen with open chest in it to appear. When it does, press & hold the Volume Up and the Power buttons.
5. Yet another menu should now appear. When it does, select Wipe Data/Factory Reset (use Volume and Power buttons).
6. Now select Yes - delete all user data > reboot system now.
7. Done! Yaay.