The Null can hear, so... would Magical Music work on them? Extrapolating from what is seen in the books, Maglor could, theoretically, use music to send them to sleep, to make things look like other things, and to affect basic emotion and perception (see things which aren't there, see things in places that they're not, that sort of thing, possibly some basic emotional manipulation ala how people have Feels about certain music). I don't know if any of this would/could apply, if at all, to sentient computers....