Disclaimer: The cables might be a bit different on your car, so this might require some improvising, but I hope the general idea works. Also, it's absolutely possible that there's a much easier method; I ain't a mechanic. Also, I thought of writing this down after the fact, and there's no force on this earth that will compel me to disconnect this unholy plastic box once again. So no video/pictures of the work being done.
Also, if you just want to change the bulbs or the PCB, opening the panel while still connected to the cables should be possible and saves you many headaches.
So this is the culprit as we all know:
On to the steps.
0. If you already failed to put this abomination back and broke the plastic, get an unbroken one. You can get it pretty cheaply from a chop shop. If you can't find one, try getting one from a Peugeot 206, it's the same thing. Just swap out the front plate. Or don't if you prefer the orange glow; I ain't judging.
1. Take out the metal clips and put the panel in the cavity. Duh.
2. Connect the yellow cable to the grey plastic actuator. The most painless way I found is having the panel in the horizontal position and moving the end of the cable to the hole and under the straight part. Then, while keeping a finger on it, rotate the panel to the vertical position. With this, you can slip the cable into the hole, and I found that the grey part holds it a lot better than the black one. Don't clip on the cable housing yet, but align it properly next to the plastic piece where you clip it in!
3. Connect the black slider piece to the 2-corner cable. This is pretty straightforward, just arch the cable and connect it. Then clip on the cable housing.
Now for the hard part.
4. Put the panel in its place properly. Rotate the fan direction knob (grey actuator) all the way counterclockwise, so the yellow cable is pretty loose next to the black actuator. Also rotate the black actuator all the way counterclockwise so it is the closest to the middle. Reach in from below (radio hole) and above so you can guide the cable and feel the actuator cause you won't be seeing this. Take the blue cable and move the end to the actuator hole. You should guide it from the bottom part of the panel and the cable should be above the yellow cable (which is pretty impossible to do if you didn't listen in step 2 and clamped that down). By "above", I mean if the base is the back surface of the panel, then moving away from that, first, there should be the yellow cable, then the blue cable. After the cable is in the hole, turn the knob so the little plastic piece gets above the cable and move the cable to its place next to the clamping location.
5. Move the panel back into the cavity. Don't rotate it! In my case, rotating it to the horizontal position always resulted in the blue cable popping out. But it might be worth a try; if it stays there, the next step is simply clipping the two cables in the horizontal position then you're done. If it pops out, just repeat step 4.
6. Well, the step is still just clipping the two cables, just a lot harder. Barely rotate the panel, so you can reach in with fingers/pliers and put the metal clips into the slots. Start with the yellow cable, clip it in, then clip in the blue one. You won't have much room, but it's certainly possible.
7. Put the panel in its place and never touch it again. Also, don't forget to connect the electrical wiring.
That should be it. Now that I read all that back, I'm less and less sure if that makes any sense. But hopefully, it helps someone.
- Spoiler: show