I’m a bit wary of enabling and disabling components, after doing a dreadful job of it in some of my own projects. So if you want to stop your zombie from moving without disabling the navmesh or indeed the enemy AI, I was able to do so quite easily with just a few lines.
In EnemyAI, add:
public void StopEnemyMovement()
{
navMesh.speed = 0;
}
then call this method on death in EnemyHealth.
Because the death state has no transitions out, you don’t have to worry about the dead zombie switching to attack animation or anything like that.