Error 1 Jura impressa XS9 Classic (13664)

Hello
,At startup my Jura impressa XS9 Classic locks on error 1. I checked the 2 sensors on the 2 thermoblocks they seem to be good because they show me about 11 Kohm at room temperature. Before displaying error 1 the machine indicates that it is heating but the thermoblocks are cold...
Would you have an idea or a test that would allow me to isolate the cause of the problem ?
Is it possible to override error 1 in order to start a descaling or even to ask for a coffee and thus check that the elements are working?
Thank you.

I add that I also tested the heating circuits and resistors. There is a good continuity and the heating resistors show me a resistance. I don't have a broken fuse.