Butter Bot has no wake word. To start it listening, give the power button a short press (or press the summon button on the controller). It plays a brief prompt, then matches whatever you say next against the phrases it knows.
That little red light is basically Butter Bot's mood ring: a slow blink means it's awake and idle, a fast blink means it's listening, and a steady glow means it's talking. Say your piece within a few seconds of the fast blink.
Changed your mind halfway through? Just say "Cancel" or "Nevermind", or press the button again and it lets the whole thing go.
Butter Bot is, at heart, an NPC with commitment issues — it listens for a set of things at any given moment and responds in character.
A few actions ask a follow-up or a yes/no question (the 8-Ball, dice, IR training, reading out notifications). Answer — "Cancel" or "Nevermind" backs you out of anything.
You can also trigger any of these actions straight from the controller, which lists every action so you can simply pick the one you want.