1/ Switch off the phone (either removing the battery or shutting down by holding the "end call" button for few seconds
2/ While being switched off, hold the "home" (house) and "back" (the arrow in the lower right corner)
3/ Hit briefly the "end call" button" while still holding the "home" and "back" buttons.
4/ Release the "home" and "back" button, a white screen containing technical information should appear, with a red message asking for hitting the "menu" button.
5/ Hit the "menu button", the Hero will now boot with factory settings.