Actually, the preventative measures Inosi took against Bai Yun weren't just the injection of Black Iron; she also implanted a magnet in Bai Yun's 'energy core', that is, the heart of our people, but this magnet had a protective layer.
If the protective layer melts, the Black Iron would rush towards Bai Yun's heart, causing the most severe heart attack—one that can't be survived without a heart transplant.
And our people have no such thing as heart transplants; each energy core is unique, incompatible with others.
So once the energy core fails, the person naturally ends up dead.
Preventing the reaction between Black Iron and the magnet is only the first step; to completely break free from Inosi's control, she needs to undergo surgery, which she can't do herself, nor can she easily find someone to do it, as it involves both her tribe and personal survival.
