in my case, i massaged it with the screen both on and off. at first, i did it with the screen on, but i got freaked out seeing the lcd getting all distorted and I was worried i was going to damage the screen. so i turned my computer off for piece of mind. it took a few times to get it to finally go away. but after massaging it for a while, i turned my computer back on and voila! the pixel was back to normal. in my case, the dead pixel was definitely a dead pixel, more specifically subpixel and not a piece of dust. it was definitely an always-on green one. during the windows start up screen the green dot was very obvious and could not have been mistaken for a piece of dust, although i’m sure it might be dust for others.
hope this helps.=\