Re-reading, it sounds like the pup may have been punished for coming in when it was younger. I've done this before when a dog finally decided to come in, and its a big mistake, because the dog knows that when it eventually comes back it will get bollocked or worse.
Some good advice here.
Patience and a long rope and treats are the way forward. The no-eye contact is good as well.
The "let him know who's boss" advice is pish, and if a dog is already cowed in certain situations will just make the dog worse (imo ).
Let us know how you get on, and good luck.