I'm using a stock A70 in my car (and only for my car, fix installed). I thought I use a hardware mod (battery dummy) to kill and start the phone with connect/disconnect the power.
But I think there has to be a solid software method to start the phone when plugged, and shut it down when unplugged.
I allready used google search, but there is nothing that works with newer samsungs.
adb shell
part. Some bootloader support properties which can be changed and allow to change the way bootloader reacts. But I don't have any experience about this on Samsung devices.