Only put it on for 10 minutes to try it now won't go out on a lead just refuses to move

Why are you using a halti on a 4 month old puppy?

Haltis are for dogs that have very bad leash manners. The Halti doesn't teach them to be good on a leash, it teaches them that they cannot pull. Take the halti off, and there right back to there old tricks.

Your pup doesn't need a halti (at this point). Teach him to walk on a collar and leash and teach him not to pull and to listen to you. He is just a baby, he has no bad habits. You have a very fresh slate on your hands. Teach him the right thing! Take back your halti and get your money back! If you need help on teaching your puppy to walk on a lead, I would suggest a puppy class.

You probably scared the puppy plus those are for older dogs just give it some time then try again