Edited:

Thanks!
STOP and MENU for three seconds worked. Oddly, it didn't work when the Apple TV was off. It worked when the Apple TV was on, though... so okay.

However, POWER doesn't work and various buttons only to work when the "cursor" is set to a particular position. This doesn't seem to be a problem if there's a list somewhere of what will work when. Where did you get that instruction? I'd like to have the whole list, if possible!

FYI: the remote appeared to be brand new as it was in a Channel Master mailer and was in a heat-sealed dual plastic bag (one section having batteries, the other section containing the remote).

Does the Apple TV have to be reset in some way?

Thanks.