Problem with my 01 Sentra GXE(California car) , car run rough(running on 3 Cylinder) . Did compression check, fine. Replace the entire fuel system. Replace #1 coil pack /spark plugs, run fine for about a week. problem came back. now come down to the ECM, bought the ECM from the dealer, but they insisted that i have it put in by them, because of some special procedure ( hook up to a scanner to reprogram or initialize it), well, after they replacethe ecm in, car doesn't even start. My question it, is there any special procedure/thing to do when replacing the ECM?