Ah!
You found out why it's actually more important to have a good ground than all the fuses, switches or an electrical loads you can muster into a piece of machinery.

Very simply put, the "ground side" is in itself is "the" complete half of the battery/electrical system. It's also the most neglected or less thought about due to its simplicity! It does move or shake, twist or pop to break.


In a true electron "theory" class in schools it is "said" that the electrons travel only in one direction. In the true sense of DC (direct current) it has to go out the negative side of the battery first and then travels back to the battery on the positive side.

Anything on the positive side of the circuits are like safeties, controllers or things using the energy. Each having a definite purpose or problem unique to itself.

It's starts the hunting because it's the way we think "naturally" to deal with a problem or problems!

In your case of inter relationships, the work you performed with that many circuits, all in one place, demonstrated the networks and its electrifying direction of operation, in a sense.
Some can make arguments to the contrary, which always exists, with other electro-mechanical types of tinkerers about our fair planet.

In a nut shell, that is all I should say.
To go any further, in my way of trying to explain things, just might make a suggestion appear on here that there is a "meat" head inside that decaying a nut shell too!

Just like a battery, it takes two sides to make a whole!

Ever tried to short the negative side using a wrench?

😋😋 Phil