Again, what is it saying when you try to login to backend? Is it saying your password is incorrect? That your secret key is incorrect? Just refreshes and displays nothing but login form again?
Your issue has nothing to do with CB, but either with Joomla itself or your user account (e.g. wrong 2FA key). I'm trying to help you as a courtesy as we do not provide support for anything except CB and our products, but you're not providing any feedback on what is happening.