There are some posts on this forum about the most curious things happening if the wires and particularly the plugs and sockets of that wire harness get corroded. I mean the harness near your left foot. Corrosion can be almost non visible, and yet create havoc.
If it were mine, I would look at every single pin of the plugs and sockets of that harness with a very strong magnifying glass. Also check where the wires are crimped onto the pins of the plugs and sockets!
The smallest amount of green corrosion contamination and it could well be the only visible thing pointing to the cause. Looking carefully doesn't cost money, just maybe half an hour's time.