Hi Neil and Matt.
Yep, as Matt states, the powder button is merely to open the powder drawer with. Pushing this button moves a lever behind the powder drawer facai and nudges the drawer out about a centimetre or two.
It looked good, as it removed the need for a handle recess on the drawer, enabling them to produce a clean flat finish across the width of the machine.
The mechanism was notoriously unreliable in my experience and used to stop working as, invariably, it got all gunked up with powder sludge or simply snapped.
As Matt states though, a simple tug under the drawer enables easy access.
The blocks you refer to, next to the programmes, symbolises what sections of the powder drawer to place powder and fabric conditioner.
Programme A = prewash .... powder only goes in the left hand part of the drawer
For programmes H, J and K fabric condiioner should be placed in the middle compartment, whilst powder should go in the right hand compartment.
Should get some better pics of it this weekend and will post some updates on the A3254 soon.
Paul