Melitta Caffeo Barista T Smart no water output

This morning when I turned on my Melitta Caffeo Barista T Smart, it started the cleaning process, but no water came out and after some 40 seconds it showed that I had to fill water in the tank, but it was almost full.
I could hear the pump running, but it sounded muted.
I have submitted the brewing completely in water for 3 hours and subsequently in a decalcing solution for also 3 hours, but the problem remains the same.
Will it help to replace the brewing unit?
Or any other suggestions?

The same problem with my machine. I took it apart. There was a chunk of lime sitting in front of an elbow. Chunk removed and the machine runs again. I have blown through all hoses and parts in turn until I found the blockage.