Melitta Solo E957-101 bean symbol flashing

Hello,
I have problem with my melitta solo.
When brewing coffe machine releases only little amount of coffe then it stops pumping water and drainage valve is letting out pressure.
I have replaced drainage valve, pressure valve seals, and all brewing unit seals except lower piston seal, I've checked all microswitches, everything looks OK.
I've tried running cleaning program, it didn't help.

Any ideas?

Is enough powder ground? If there is too little powder in the brewing chamber, the coffee withdrawal stops and the bean symbol flashes.

I've made it working again! I didn't check one microswitch... the one that is triggered when brewing chamber is in top position. Someone connected the wires to wrong connectors on microswitch. I've purchased this machine broken so I don't know it's history.