I am always very happy to help people if I can, but I personally feel a bit sick when I see endless lists of voltage measurements and i usually just pass by. I have no idea how the other techs on this forum feel about that, but fact you didn’t get any answer gives me a hint.
However, getting to your problem..if I had an issue such as yours, I’d rule out a charging port fault and head straight for Tristar replacement which is coherent with the “charging when turned off” behavior and with use of “OEM” cables. BTW, there are no OEM cables in the market, closest you can get is third party MFI certified but one always needs to check Apple’s database as big marketplaces are full of sellers claiming MFI compliance they don’t have in reality. Hope that helps.