To Fail or Not to Fail

One of our children is currently flirting with failing a class.  The child is capable, and moreover, the parents and teacher are all willing and able to help, but the child is pushing everyone away.

Both of my children are hard-headed and often refuse to be teachable. I'm pretty sure this is a result of bad parenting, but it is where we are now.  So how do we go forward?

Yes, we can hire a tutor. Yes, we have taken away electronics of any kind. Yes, we are willing to take away extracurricular activities such as the sport the child plays and the scout and youth group activities.

I'm wondering if letting the child fail the class will solve the problem or make it worse.  Any thoughts?