If you mean the Touch ID button flex cable broke(the little grey metal rectangle attached to the flex itself broke),it is repairable by a microsolderer. Other than that,you can maybe go to accessibility settings,assistive Touch. This allows a virtual home button function on screen.
The Touch ID function is tied by software to the logic board itself. So it is not replaceable unless apple will program a new one,which they would not do since you’ve opened the iPad…you can buy a home button replacement,but you will lose Touch ID function. Only physically pressing will work.
The only way to repair your Touch ID flex cable is to have someone that microsolderer tiny things fix it for you.