I used factory ecu, switch and I tapped the dash. My RR DIFF light never blinked like factory but it could have been because I didn't connect every wire the ECU had coming out of it. I would push the button, no light, but when I heard the e locker engage the light would illuminate simultaneously. I don't remember if it would engage if the key was in the accessory mode but I guess it depends on where you're getting your power.
Did you try the screwdriver method to get the locker turned over?