How to call Animator from another script

Hey I have a diying animation but it's not played by the script. This is my code:

     static Animator anim;
     GameManager instanceGM;
 
     private void Awake()
     {
         instanceGM = GameManager.instance;
         agent = EnemyController.instance;
 
         anim = instanceGM.player.GetComponent<Animator>();
     }

     void OnTriggerEnter(Collider col)
     {
 
             //Debug.Log(col.gameObject.tag);
         if (col.gameObject.CompareTag("player"))
         {
             Debug.Log("Player died");
             anim.SetBool("isDead", true);
             StartCoroutine("WaitForAnim");
             
         }
 }


 IEnumerator WaitForAnim()
 {
 while (true)
 {
     instanceGM.player.GetComponent<BoxCollider>().enabled = false;
     yield return new WaitForSeconds(2);
     instanceGM.player.GetComponent<BoxCollider>().enabled = true;
 }
 }

And this is the GameManager:

 public GameObject player;

 public static GameManager instance;

     private void Awake()
     {
         //instances for variables
         instance = this;
     }

Do you know what I am doing wrong?