It was the Residual Current Device (that big thing that was burned in one of the holes) that was defect and a mistake on the wiring.
It failed to cut the energy, alongside the two cables shown on the picture being "misconnected" (the two cables were actually on that same burned hole, instead of being separated), according to the electrician. The Residual Current Device, that metal thingy that was also burned which name i don't know and the two wires got replaced. 190 bucks.
You can see the whole box (with the damaged RCD) on a previous post.
Thankfully, it is fixed. If i had waited some days longer, it would have catch fire and the results would be tremendously disastrous.