does that mean that you have to do 2 damage or less on the whole dial
or just at least 1 slot of 2 damage or less somewhere on the dial

You simply just need a damage value of 2 or less somewhere on the dial in order to use it. For more of Nanobot questionings, try this thread.

just one it seems, since the DR rules say it doesnt have to be on the 1st click or all clicks either. Any click with 2 damage or less will do.

Well, you can ASSIGN it to any character with one or more clicks of the pre-req, but in order to actually USE it, the pre-req has to be showing at the time the character attempts to do so.

So if the character only has one click ot 2 or less damage, it's not a great card to assign to him. OTOH, if the character only has a couple clicks of MORE than 2 damage, then it can be a GREAT card.