On this link you can follow the steps to do a factory reset:
Below you can follow the steps as well:
1. Disconnect STB with the button from below*
2. Press STB’s button from below for about 8s (led is blinking in green) until the led switch to red.
3. Release the button
4. Press menu button from remote until the menu scroll appears on the screen.
5. Scroll down with the cursor and select ‘System’ pressing right cursor or 'OK' button.
6. Do ‘Remove Software’ and ‘Factory Reset’.
7. Press left and down cursors and then ‘Exit’.
*see attached image