Unity – I need to flash that jerk?

I need that idiot to flash:

Enter image description here

… but not literally. This is a 3D game object that faces the camera and has an unlit texture. I need to "flicker" the object to indicate that the item was received. The object must be created at the moment when the lid opens (ready), remains unlocked until the lid jumps all the way up, and flashes three times during the 0.6 second in which the lid is open. The feces are destroyed as soon as the lid falls down again. My code (flashing / flashing does not work)

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ItemBox : MonoBehaviour
{

    bool disabled = false;
    private Animator anim;
    public GameObject item = null;

    void Start()
    {
        anim = GetComponent();        
        if (!disabled)
        {
            anim.Play("ItemBoxIdleState");
        }
    }

    // Update is called once per frame
    void Update()
    {

    }

    void OnTriggerEnter (Collider other)
    {
        if (!disabled && other.gameObject.tag == "Player")
        {
            anim.Play("ItemBoxGetItemState");
            GameObject itemClone = Instantiate(item, transform.position + new Vector3(0, 0.5f, 0), Camera.main.transform.rotation * Quaternion.Euler(0,180,0));
            Blink(itemClone);
            Destroy(itemClone, 0.8f);
            disabled = true;
        }
    }

    IEnumerator Blink(GameObject obj)
    {
        Renderer objRenderer = obj.GetComponent();
        objRenderer.enabled = true;
        yield return new WaitForSeconds(0.2f);

        for (int i = 0; i < 3; i++)
        {
            objRenderer.enabled = false;
            yield return new WaitForSeconds(0.1f);
            objRenderer.enabled = true;
            yield return new WaitForSeconds(0.1f);
        }
    }
}