Dishwasher Bosch SMS40E32EU, How to view error code?

Hi, I'm trying to repair a Bosch Dishwasher SMS40E32EU and my very first problem is that the control panel is so basic that I can't figure what is the error. The true is, some times wen the machine is rising, the "Tapper led" turn on . as far as I know, in accordance with the user manual, this is the only error lamp and mean lack of water , drain pump failure or general error.

I already check several parts (like tapper filter blockage, flow sensor problems, drain pump blocked) and keep not finding the problem, so my questions are:

Is there a way to know the "error number" via the control panel (like a keys sequence or so) ?

_Is there on the market some diagnose board to connect to this machines and know what is the error?

Thank you