I'd have to have a bit of fun with such a caller, as well. The "sequence of keystrokes" is probably to start up the remote assistance feature, or a link to a compromised website. I'd say I'm entering the details, while brewing up...
Then I'd see how much effort he put into "computer support" trying to establish why he can't hack into the PC. When he's finally losing the will to live, I'd say "Oh wait a minute - it's not switched on"