So I just had this issue, my own fault because there was way too much snow on the back hatch and my snow brush was back there. The info in the manual didn't work for me either, but I didn't want to give up, so kept going. I tried the routine holding the button opening closing, no good. During all this the latch was unlatched, so just to try something different I used my key to close the latch with the gate still open. Manually closed the tailgate and tried the procedure from the manual again and this time it worked. So the key seems to be that the latch has to be closed for the reset procedure to work.