You've got the kart, and though it's not a competitive LTO (left turn only) kart, it could be run on the dirt. If your son likes it, the dirt racing, after a few races, you could then buy you a true LTO kart. It all depends on how much money you've got to spend. You could sell the kart you have, maybe, and hopefully, not lose too much money. If you can do that, I think you would be better off.
You can look at it this way; this is your 1st mistake, let me assure you, there will be many more to come, and it's how you recover from those mistakes that counts. I hope it doesn't put you off on kart racing.
Find a kart track and attend a couple of races. Watch the lineups, see what's competitive, talk to people, Karter's love to talk about their karts.