I’ll confess this as it is fairly funny….
Whilst working on my 3D printer (Creality K1), I was removing the jotend board. As I was struggling to remove a recessed cap screw, I had the brainwave to fish it out with a magnet. Had the printer not been powered on, this would have probably been ok. The magnet shorted out something and stuck to the board fairly well! The amount of sparks and the resulting coukd of smoke was quite impressive.
The board was, predictably, “toast”! Luckily I had a spare hotend board and after swapping it out, the printer still works!
We all make mistakes!
Jimb