Countdown after resume game.

Hey! I'm currently working on a mobile game and I'm trying to make a countdown timer after you unpause the game. I followed a tutorial to make it but it never worked for me. Here is my code, I would love any help/suggestions:

 //method number one for time(not working)
     IEnumerator cdToStart()
     {
         Debug.Log("TIME SHOULD START");
         while (cdTime > 0)
         {
             Debug.Log("TIME AT " + cdTime);
             cdDisplay.text = cdTime.ToString();
             yield return new WaitForSeconds(1f);
             cdTime--;
         }
 
         cdDisplay.text = "GO!";
 
         Time.timeScale = 1f;
         isPaused = false;
         
         yield return new WaitForSeconds(1f);
 
         CountDownUI.SetActive(false); 
 
     }
 
 //method number two for time(not working)
     IEnumerator Countdown(int seconds)
     {
         int counter = seconds;
         while (counter > 0)
         {
             yield return new WaitForSeconds(1);
             counter--;
             cdDisplay.text = counter.ToString();
         }
         cdDisplay.text = "GO!";
 
         yield return new WaitForSeconds(1);
 
         Time.timeScale = 1f;
         isPaused = false;
         CountDownUI.SetActive(false);
 
     }
 
 public void resumeGame()
     {
         pauseMenuUI.SetActive(false);
         CountDownUI.SetActive(true);
         Debug.Log("YOU PRESSED IT");
         //StartCoroutine(cdToStart());
         StartCoroutine(Countdown(5));
     }