Error 3

Hello, I have an Eppendorf 5415R centrifuge that keeps showing ERROR 3, even before I check all the sensors on it. Even before I turn it off and after 10 minutes, the error 3 remains. Can anyone help me with this? I have good electronics skills. I can't buy the electronic main board or send the centrifuge to an authorized service center in my country because they said the centrifuge has been discontinued. I would be very grateful if anyone could help, thanks. Renato.