I was also going to suggest music. It might help to mask some of the noise from your other animals. I have used harp music for cats.
You need to stop fretting so much. You are scared and he is picking upon it! Calm down, throw in some temptation treats, cover more of the cage, stop lifting the cover off maybe leave one corner up. Tap lightly as you come into the room, tell him being stubborn will do no good and he is going to stay safe and loved with you and you will protect him. Tell him all about your other pets and that you will be going away and he needs to go with you cause no one will take care of him once you are gone. He's smart and savvy and pulling this stunt on you worked before so he is trying it again. Those idiots who left him in the trap for 6 days do NOT know what they are tr talking about when they tell you how vicious he is. They failed him and DO NOT want you to succeed! He is probably afraid you are going to abandon him too so keep visiting him but stop hovering, STAY CALM and instead of conjuring dire possible scenarios concentrate on positive ones. He is hoping you will let him go because he can sense your agitation and does not yet realize how great being inside will be. Did you check out the gloves I posted? If they are sold out others on there I saw were just as secure. Get a face shield and wear a heavy jacket and leather gloves. If you let him go he will have no one when you leave. Barn cats can become prey very easily and since the idiots won't allow you to check things out prior to turning him over to them dont't trust them. Remember they are the reason he is so scared of traps. They don't want you to help him when they wouldn't or couldn't. He is sensing how upset you are so stop. Go toI will not put him in a barn program since he'd be better taking his chances in his own territory.
If the vet said I had 24 hours before he gets sick - I will let him go if he doesn't eat or move by tomorrow. Believe me, I don't want to but if he is so stressed he will not eat after 3 full days - or drink water - I cannot continue it.