The SX20 can be factory reset in several ways: By issuing the xAPI command: xcommand systemunit FactoryReset Confirm: Yes

By removing the config.db file.

By using the Touch panel: More - Settings - Administrator Settings - Reset

Turn off unit (e.g by holding the physical power button pressed until it shuts down). Then hold the button for 10 seconds until it starts blinking. Now press the button twice. The unit will factory reset and restart.