Honestly can’t imagine a scenario where this turns out well. You say his business makes money, but I gotta call cap on that seeing as he’s behind on bills and taxes. And I know you want to give him a gold star for his efforts and deflect the blame for the situation the businesses in. But take a good hard look

Literally the best case scenario is that his partners siphoned physical cash away from the business over time. If your brother was so ill informed to not catch something so egregious, that really calls into question his management skills. Would you really trust someone so out of touch?