dwangrem is indeed emergency brake, but the phrase should be translated as 'emergency brake active and deadman operated' or 'emergency brake enabled and deadman operated'. With regard to the two options for the emergency brake, one can only decide from the context. It seems rather unlikely that the emergency brake could (or would) be disabled during normal operation (that would usually be foolish), but it may be possible. As for the deadman, it must be operated periodically by the driver to indicate that he is present and awake (formerly a pedal was used, but it's easy to just put a brick on a pedal, so now a button is used, and it must be periodically pressed by the driver).