Which step is NOT required for a disabled Siemens train?

In the context of evaluating steps necessary for a disabled Siemens train, activating the brake pressure alarm is not required because the alarm serves as an indication system rather than a procedural step that directly contributes to the resolution or diagnosis of the issue at hand.

When dealing with a disabled train, the primary focus is usually on ensuring that systems are correctly set up and isolated for safety and operational control. Setting the pilot valve, isolating the coupler non-electrically, and conducting a continuity test with the reverser in neutral are all critical steps that help to verify the train's operational state and ensure it can be analyzed or safely moved.

In contrast, activating the brake pressure alarm does not aid in the troubleshooting or repair process; it's simply a warning system designed to alert personnel to existing conditions rather than a necessary action to be taken during the fault finding or remediation process. Thus, this step can be excluded when outlining actions required for handling a disabled Siemens train.