script.Lighting.PlayerGUI.Open
Im sorry, But im a rookie scripter.
The answer is no.
By 'opening a gui' I assume you mean to be able to see it?
A GUI has a property of Visible
controlled by a boolean
(Yes or no)
So to 'open' a gui you'd need to use;
script.Lighting.PlayerGUI.Visible = true
and to 'close' the gui you'd need to use;
script.Lighting.PlayerGUI.Visible = false
If this is not what you meant, do tell me.
If this answered your question please accept my answer with the button on the right. If it was not clear or did not answer your question please do say =)