Also, the wites leading to the switch seem like 0.05” IDC cable, which is horribly inadequate for mains application. The “jumper” is not some kind of low power

Also, the wites leading to the switch seem like 0.05” IDC cable, which is horribly inadequate for mains application. The “jumper” is not some kind of low power config input, it simply shorts the midpoint of DC smoothing capacitor bank to neutral mains wire and thus is both live and conducts significant current.