What is one step in troubleshooting a train that does not have a release light?

When troubleshooting a train that does not have a release light, looking for open doors is a crucial step. This is because open doors can create a safety hazard and may prevent certain systems from functioning properly, including the release light mechanism. If a door is not securely closed, it can interrupt the electrical circuits or sensors that are designed to detect the readiness of the train, which in turn may inhibit the illumination of the release light. Therefore, ensuring that all doors are properly closed and secured is an essential part of the troubleshooting process to restore normal operation and functionality of the train equipment.