4 weeks is nothing for a BP to go without food. Many of them fast for months every winter due to breeding season. It is a little more concerning with a hatchling than an adult, but 4 weeks is still not enough to get panicked as long as the snake is otherwise healthy.

I would advise getting a digital scale if you don't already have one so you can monitor your baby's weight. If you start to see a significant drop in weight that can't be explained by waste elimination, that is when you should start to get worried.

Do you know what pro-exotics was feeding this little guy? Mice? Rats? Live? F/T? What size? It might help if you offer as close to exactly what he was used to until you get him eating again. I would NOT go with the gerbil scenting.

Wait a full 7 days in between feeding attempts. Too many feeding attempts can just add to the snake's stress level and cause more refusals. Also, you really need to refrain from handling him until he starts eating. If you take proper care of him, you will have your pet for many many years to come. Be patient. Yes, I know it is hard!

You mentioned your temps. Are you measuring with a digital thermometer? It might help if you can get your cool end a little warmer so it does not go below 80.

Are you measuring your humidity? Is it in the right range, around 50-60%?

Does the snake have at least 2 (one warm end, one cool end) hides that are snug fitting so he'll feel secure?