Laptop Monitor dying, want a second opinion

Hello, my GF has a Dell Latitude D600 (very old) laptop that has been working fine for a few years when she suddenly started having a weird problem.

Her screen goes lighter, then darker, then lighter again, and then black.

If I press the "closed lid" button, wait for the laptop to enter standby mode and then tap the button again the problem goes away for a little while.

I'm a computer technician by trade, and I was considering telling her to replace the screen but first I wanted to be sure that it was the monitor's fault and not something else. My line of reasoning was that the wires that connect the monitor to the motherboard might be worn out but without stripping them I cannot be 100% sure.