Are you doing some training? Because it sounds like there might be more problems underneath which can be fixed with a good trainer, for a better quality of life for Brownie. Try to find a respected (!) trainer, don't watch tiktok or youtube. They can work wonders and you two will have a better understanding of each other and your relation.
But first, lose the chain. You have to respect this for now. He just needs to feel safe with you, maybe you can redirect his attention later with some play or a walk. If you really want to keep the chain you have to do training, but without knowing the dogs character I can only speculate how long this will take.