I'm having a similar ish problem with mine. It did work perfectly, and it's now stuck in the up position. My switch isn't lighting up though now, it was previously. I've had the fusebox up and the maxi-fuse is fine. The only other thing I've done is fit an android unit and rear camera, so tapped into the reversing light connector at the back. I did wonder if I hadn't plugged something back in, there seem to be a few plugs in that back corner not plugged up to anything but I can't see anything that they would plug into anyway. I've got a pic I'll have to get off my phone, because there's one plug that I've seen a youtube video of another person's car where that plug seems to be plugged into something whereas mine doesn't seem to have anything to plug it into.
It seems very bizarre. The electrics on these are a bit bonkers aren't they.