Siemens EQ. 9 S300

A wonderful good evening wishes I Through Google I have found the forum which has brought me one or two times further. I have a Siemens EQ. 9 S300Nun yes but it does not work anymore. After switching on and the test with the brew group the error message appears: Please let the appliance cool down. By a similar post I could read out that it is often times the coal and or the grinder. I have now ordered a new one, just installed and tested it. Unfortunately the error is still there. I have now a new ceramic valve still lie. The question is can it be that at all ? Does anyone else have a solution for me ? Would be a pity to hand it over otherwise Technically I am at least one. "A little" talented but with little instructions on how to do what if anyone has a solution I would be happy to hear from you.
I thank you already heartily and stay healthy