I doubt he will be back after this latest attempt, now he knows for sure there is an alarm now so there really is no way for him to steal the thing and not get caught. If he does come back; dumbest car thief ever? He wont be attempting to steal cars much longer with skills like that, he'll get caught soon enough. Report it to the cops though in case it does happen again to cover your ass in case of a future confrontation and they will increase their patrols in the area, it's even more helpful if you can tell them the time frame it happens in.
If you see him outside working on your car, don't scare him off with a flashlight. Call the cops and tell them to come with their sirens off and watch him quietly until they get there so that way he actually gets caught. It's not like he going to be able to steal your car anyway with you watching him, especially if you have a remote alarm. Just trigger the alarm or shine the flashlight if you feel he's actually going to successfully get into your car and start it before the cops get there. Which takes quite a bit of time for someone who even knows what they are doing exactly.
That and GPS trackers in case you car actually does get stolen so it can be easily located by the police, and even shut off remotely leaving the thief stranded and screwed when the cops roll up. Garages are also really the only way to truly protect your car from everything and anything happening to it.