Atoner probe (also known as a tone generator and probe) is the best tool for tracing and identifying cables in a patch panel or wall jack. The tone generator sends a signal through the wire, and the probe helps locate the cable by detecting the tone.

The error message "HDMI2 no signal found" indicates that the projector is set to an input source that is not currently receiving a video signal. Input source selection is one of the first items to verify when an external display shows a black screen but powers on correctly.
Many projectors have multiple HDMI ports (HDMI1, HDMI2, etc.). If the PC is connected to a different HDMI port than the one currently selected, the projector will display a "no signal" message even though the cable and device are functioning properly. Changing the input source to match the connected HDMI port resolves the issue quickly.