Dead line of pixels: check a full row or column

A vertical or horizontal line should be compared across the monitor menu, input source, and solid test colors before blaming the panel.

Check the line first

Record the full row or column, its position, length, and the date. A whole line needs a different check from a single suspect point.
Use the screen test in fullscreen on white, black, red, green, and blue. Note whether the line stays in exactly the same position.
Open the display's own menu over the line and check whether the mark passes through the menu as well.
Try a known-working cable and another source or device, changing one connection at a time. Photograph the line and note which checks still show it.

Run the check

Use the four checks above before deciding which layer needs support.

Read the result

A single point calls for the laptop pixel guide; a full row or column needs line diagnosis. A line visible over the monitor's own menu suggests a display-side issue. One source or cable only points toward the signal path. Compare the same image in another app before deciding, then give support the model, photos, date, and cable/source results.

Limits and next step

The browser only renders patterns. It cannot inspect panel drivers, internal ribbon connections, or cable integrity, and software cannot promise to repair a physical line. Check the model's current service and warranty terms before authorising work.

Repeat the check after changing one setting or connection. Keep a record of what changed before deciding whether the device needs service.