Coffee machine displays 'Refill water

Hello, everyone,

Unfortunately my Siemens EQ5 coffee machine is defective. The machine always indicates that you should refill water, although the tank is well filled and has been turned off and on several times. It's not the tank or this water level measuring magnet (I mean the round plate that rises when you add water). We have already checked this. It must be something technical. We suspect the flow sensor or the pump. Is that possible? How can you check something like that?

Maybe somebody can help me. Thanks for the answer and best regards.

I also have this problem on my TK76K573 built-in machine. It started with the milk system not being cleaned, then the hot water didn't work anymore and now there is no more coffee.

Also for me the question arises what kind of defect it could be?
Could it possibly
be
a water pump or a
drive?
I am happy about every contribution, thanks!