Garrett fired. Callahan fired. Try to hire a college coach with intelligence and passion (maybe Urban Meyer?) to be HC. Hire a real GM.
Draw clear lines of responsibility between HC and GM and hold them accountable. Empower them to control their staffs and their players to achieve objectives. Step away, place my trust in them, and let them do what I hired them to do. At the end of the year judge against clearly drawn responsibilities. If either didn't meet the expectations fire them and hire another. Repeat.
You know, what most successful owners do.