The 4 windows, rear window lock, sunroof and electric mirror switches are all soldered onto a PCB along with some electronics and a large chip!
i tried checking mine with multimeter but as there connected to other things its dificult to get a propper reading and they may be fine and other stuff on the PCB may be buggered!
the switch pack will send the relevant signal to the BeCM, not sure if the switch pack is concidered an ECU but i know what you mean.
Easiest way is to swap with another vehicle but not many of us have 2 P38s though! dam that lottery............
(im lucky as boydonegood (from this forum) lives round the corner and he has 2!)