Miele W 320 Operating Instructions Manual page 42

For safety reasons the drum door cannot be opened when the suds temperature
is higher than 55°C.
42
Put the plug in the socket and switch on.
Switch the machine on with the I-ON/0-OFF button.
Open the drum door as described in the section
"Opening the door in the event of a power failure".
Press hard against the lock side of the drum door
and then press the Door button.
Clean the fluff (drain) filter and the drain pump.