If a customer's audio is playing but there is no video display, what should the technician check first?

In the scenario where audio is playing but there is no video display, the most logical initial step is to check whether the TV set is powered on. This is fundamental because even if audio is functioning, the absence of a video display often indicates a more basic issue such as the TV not receiving power. If the TV is off or in a power-saving mode, it would not display any video output, despite any signals being sent to it.

The functionality of the TV set is critical as it serves as the medium for both audio and video. Ensuring that the power is on can quickly rule out a simple yet fundamental issue before moving on to investigate more complex problems related to signal integrity, content delivery, or audio configurations. By addressing the power state of the television first, technicians can streamline the troubleshooting process.