Sorry but the first comment by blueloo said "a CSM popped a slide before the aerobridge approached". Based on that statement and my personal observations of cabin crew on 737's opening the door from the inside I incorrectly assumed Qantas procedure was for the crew inside to open the doors....
Hence my comment regarding opening from the outside a better option.
I realise the 737 will not disarm the door by opening from the outside as it needs the crew to physically remove the girt bar on the floor...( old style!! )