S2 Mini UART communication fails using Serial.println on ArduinoIDE

[DavidMR91]

My S2 Mini, you can use the USB to upload code, but while running, the USB port is disabled. In the documentation it does not specify:

• What are the RX and TX pins to avoid using them by mistake
• If the USB on the PCB is Serial0 or if it is an additional serial port
• If the USB only serves to upload code or if it also allows communication with the running code