your post is very hazy on details but if you allowed a test ride its not stolen you gave possession to the test rider it's like loaning your car and providing the keys. You made a huge tactical error you should never allow test rides unless you are holding payment in full. I suggest you move on and put this behind you because you gave the board away it wasn't stolen you will never be able to get it back even if you find it. if they get hurt on it you might even get sued