I'm not sure what you mean by reset, but if you want to attempt to download the latest version of the set-top box software - this might be the same as a reset, then unplug your digibox. wait 10 seconds. Press BACKUP, and keeping it pressed until you get a message on screen, plug the digibox back in. The message will only be displayed if your box is connected to your TV via SCART.
What is this battery trick you mentioned?