You have received a Sifa-Emergency Brake Application ("Deadman-Device"), because despite the Sifa Light and the Sifa Buzzer, not pressed the Sifa Key (Spacebar). This must be operated at least approximately every 30 seconds, to indicate to the System, that you are still conscious.

Press the Sifa-Key (Spacebar) to cancel the Emergency Brake Application, return the Throttle back to 0 (mandatory to prevent an accidental movement once the Sifa is reset). Throttle can now be notched up to begin moving again.