Delonghi Esam04.350 - Water circuit empty

Delonghi Esam04.350

Delonghi Empty Circuit – Fill Circuit.

The machine display (Empty Circuit – Fill Circuit). When I press ok the machine makes low click sound but nothing happen. I’ve tried to fill the flowmeter manually according to some YouTube video I watched, I also tried to check the filter but nothing changed.
When I press ok to fill the circuit on the machine, I can hear low click sound but nothing happen. The machine still clean itself when I turn it on (water comes out) I also still can descale the machine but I can’t get coffee of hot water, I can’t even see the coffee menu as the machine stuck on fill the circuit message.
Online, people suggested to change the flow meter, generator, heating element among many other parts. I don’t mind changing one part but I don’t want to start changing all the parts one by one.
I wonder if anyone had similar issue and know exactly which part I should change?
Many thanks in advance.