How do you make Billboard Guis enabled depending on Player's Backpacks?

Hey, people! I'm trying to make a Billboard Gui that becomes enabled if a certain tool named HackPhone is inside a Player's Backpack and un-enabled if it's not. The following Localscript is inside an Image Button inside the Billboard Gui. Can anyone tell me what the problem is? Thank you!

local Player = game.Players.LocalPlayer
while true do
	phone = Player.Backpack:FindFirstChild("HackPhone")
	if phone then
	script.Parent.Visible = true
	else
	script.Parent.Visible = false
	end
end

So far all you're doing is telling the script inside the button, that if the phone is there, enable the GUI. You aren't telling it to connect to the phone in any way. Hope I helped.