How do switch scene with singleton pattern unity3d C#

I have to two UI text . One timer script and one score script .The scenes won't switch when the countdown timer reaches zero. Will dont destroy on load work if I a call that function in the score script change the scene ? I have points set to 50 . The scene will only change if the score is below 50 and the timer reach zero. Here are my script.

using UnityEngine; using System.Collections; using UnityEngine.UI; using UnityEngine.SceneManagement; public class Game : MonoBehaviour {

private MyClockScript myClock; void Start () { myClock = GetComponent(); }

 // Update is called once per frame
 void Update () {
  if (myClock.m_leftTime < 0 || GameManagerSingleton.score > 0)
        {
            SceneManager.LoadScene("ui");
        }
 }

}

public class GameManagerSingleton : MonoBehaviour { public static GameManagerSingleton instance = null;

  public static int score;
  


  private Text text;
  
  void Awake()
  {
      text = GetComponent <Text> ();
      score = 0;
      if (instance != null && instance != this)
          Destroy(gameObject);    // Ensures that there aren't multiple Singletons
 
      instance = this;
  }
  
  void Update()
  {
     text.text = "Score: " + score;
      Debug.Log("Score: " + score);
  }
 
 

}