If you replace just the ECM and try to start the car it will brick the PCM as a security feature. If you change all the items mentioned above SKM, PCM, ECM, door locks, and if you live in NYS it will not pass state inspection as it will trigger a VIN number mismatch. I had this happen when rats chewed my wiring harness while my 3.5 02 300m special was in storage and I tried to start it, I put 12v down the the 5v buss. The ECM and the harness is now NS1, my dealer could not program an ECM for me as they no longer have the tools, too old they said. I found a used ECM on Copart that I sent to a company for reprograming, they needed my secret car number ( the dealer gave that to me) , the vin number, and the mileage to the tenth.
My dealer is the one who told me it will brick both the PCM with an ECM swap and no programming , perhaps with a PCM /SKIM swap and you follow your procedure it would work. My combo of swapping every thing allowed the car to run but then failed my states inspection due to the VIN mismatch.Actually not 100% true. If you try to start 3x times with a bad combo of PCM/SKIMM you will get locked out where the starter will not engage.
After that you put a battery charger on and turn the ignition key to the "Run" position for around 45 minutes and it will reset.