I had exactly the same problem.
Having prodded and poked every conceivable piece of plastic I found that if you leaver out the two steam buttons there is a screw underneath (Same tamperproof Star Screw with pin in middle as the screw at the back)
Finally there is yet another screw. To get to this you will need to Prise the Handle from the rear of the iron so that the handle is completely detached.
The screw can be seen towards the front of the iron
It's larger star type screw without a centre pin.
I hope that it will have been worthwhile.
I found that the main connection to the element had burned out so the Iron is beyond repair anyway. It was worth a try though.
Nick
January 2010