Thanks for welcoming me and for your suggestion, Michael.
I have tried a few times to unplug the box, waiting a few minutes, and plugging it back; to no avail.
I have a horizon box, and do not know how to do a channel scan, as you have suggested. I believe this would be suitable for someone with a digicard, which uses the tv to change channels, but I may be wrong…
Best,
F.