how to make a part need to stay on a button?

im making a puzzle game and one of the main things is putting a part on a buton to open a door. i made a simple script that changes the button's color when you put the part on it.

script.Parent.Touched:connect(function(hit)
	if hit.Name == "qb" then 
		
		script.Parent.BrickColor = BrickColor.new("Really red")
		
	end
end)

how do i make it so that the color changes back when thepart stops standing on the button? i will change the color changing into opening doors later.

Here is how you can use invalidinvoke's suggestion TouchEnded event

script.Parent.Touched:connect(function(hit)
    if hit.Name == "qb" then 
        script.Parent.BrickColor = BrickColor.new("Really red")
	script.Parent.TouchEnded:Connect(function(HitEnd)
	--do stuff

    end
end)

Hope this helps!!