Will this cable fix my Y500's blank or flickering screen?

Only if the cable is the cause. Test by moving the lid: if the image cuts in and out with movement, the cable is a likely culprit. A dead backlight or a cracked panel needs different parts.

Is it compatible with every Ideapad Y500?

It is listed for the Y500. Lenovo shipped the Y500 in several configurations, so compare the connector shape and cable routing with the old cable before ordering.

Do I need to remove the screen to fit it?

Yes. The cable runs through the hinge from the mainboard to the panel, so the bottom cover and usually the display bezel come off. Take photos of the old routing before you pull it out.

Does it come with instructions or tools?

No. It is the cable only. You need your own screwdrivers, a plastic pry tool and a repair guide for the Y500.

How do I know the cable and not the panel is faulty?

A faint image visible under a flashlight points to backlight or inverter issues, while colored lines or a garbled picture can mean the cable or its connectors. Reseating the old cable first is the cheapest test.