We had this. Tried the above plus various versions of filling the base with hot water. There is also a video about how to take the bottom off to remove the pump and check for a blockage. This was relatively easy to do BUT when I did it one of the internal pipes split (it was pretty old and brittle)
Miele have a great customer service dept - they emailed me schematics etc and I was able to send them photos.
Ended up getting a service engineer out who identified a broken part and replaced it straight away. Cost around £100 all in.
Tldr. Might be fucked, call miele