Granpa why can't we work on the LED airplane soldering kit, this circuit board doesn't look fun! :'(
Son, I retired as a Boeing engineer years ago. Touching planes now just...
It just gives me nightmares OKAY ?!
When welding battery packs, always remember to provide a good earth return through your middle finger [ these could be isolated ferules or you just got unlucky ]
The DC power plug is for decoration as this battery welder runs off of the batteries being welded (If in doubt RTFM)