It went into you garage because the garage was in the way of going from here to there. Nothing in the evolution of turtles has told them what to do about garages. It looks like it went in head first and couldn't back up - no "reverse" gear for turtles! They have their mind set on which way they want to go and will go that way no matter what. When I stop for turtles on the road, I always make sure to carry them to the side they were heading, otherwise they'll try to cross again after I'm gone.