There is a hidden system test menu on the ST5
To get to this you first need to reboot the box (press Fn on the remote and select reboot)
"C111" will display on the digital display as the box reboots. When it does this press and hold the ch up button on the sat box (not remote) "RESR" wil display, release the button, "7ES7" will display.
System test menu will now be on the tv screen.
This can the be used to test most of the st5 functions and or reset the box to defaults
Pressing the "Fn" button again will display the usb drive
To leave this screen you will need to switch the sat box off
Note must use scart to see this.
Thanks to the spain'ish guy Toffee who I managed to translate this from