Switch off at mains
Wait 10 seconds or so
Whilst holding in the "back up" button on the front of the dodgibox (NOT on the remote) switch the mains back on. - you may need two people or very long arms/
Hold in the backup button until the lights start flashing on the front of the box.
Sit back and wait can take 5 to 10 mins.
It is finished when you can switch it back on with the remote