If you want as little devices as possible, you could do the following:
- Set up the laptop to power on when the charger is connected. You might also need to enable standalone operation mode in BIOS for the laptop to boot without midplate, but I’m not sure…
- Remove the battery
- Install the empty expansion bay shell instead of the dGPU (dGPU module has USB) if you have one.
- Unplug the display/webcam ribbons (webcam is USB)
- Unplug power button ribbon
- Remove the WiFi/Bluetooth card (it might have USB wired to it)
- Remove the SSD
- Remove all input modules, expansion modules and midplate
- Install one HDMI module into the port that supports display out, plug in a monitor through it
- Plug in a flash drive/disk drive with a bootable version of some Live Linux distro
- Plug in the charger and see whether the issue persists after booting.
- If it doesn’t, perform these steps:
- I’m not sure if the mid-plate is fully hot-plugable, so maybe shut down the computer just in case
- Install the mid-plate and plug in the ribbon cable into the motherboard
- Add input modules one by one until you start seeing the issue
That’s what I’d do to see if the bare minimum configuration still has this issue. Just a suggestion if you want one. I understand that it’s not easy and you’re already tired with troubleshooting this thing.