How do I stop a scene from switching from switch before the Countdown timer reaches zero

Hello I am having a problem figuring out how to stop the scene from switch when I kill one enemy . I have one of my enemy score value at 40 and I also have a countdown timer in my scene . I need to access countdown timer and score manager script . What I am trying to do is have an set score the player has to reach in the scene. For example if the first level require 50 points before the countdown timer reaches zero then the player moves on to the next level . I just need to access both of those scripts. Have my countdown timer and score manager script here :

Score Script

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class ScoreManager : MonoBehaviour {
public static int score;
public Text text;

	void Awake () 
	{	
		text = GetComponent <Text> ();
		score = 0;
	}
	

	void Update () 
	{
		text.text = "Score :" + score;
	}
}

Countdown Timer Script

using UnityEngine;
 using UnityEngine.UI;
 
 public class MyClock : MonoBehaviour
 {
     public int  Minutes = 0;
     public int  Seconds = 0;
 
     private Text    m_text;
     private float   m_leftTime;
 
     private void Awake()
     {
         m_text = GetComponent<Text>();
         m_leftTime = GetInitialTime();
     }
 
     private void Update()
     {
         if (m_leftTime > 0f)
         {
             //  Update countdown clock
             m_leftTime -= Time.deltaTime;
             Minutes = GetLeftMinutes();
             Seconds = GetLeftSeconds();
 
             //  Show current clock
             if (m_leftTime > 0f)
             {
                 m_text.text = "Time : " + Minutes + ":" + Seconds.ToString("00");
             }
             else
             {
                 //  The countdown clock has finished
                 m_text.text = "Time : 0:00";
             }
         }
     }
 
     private float GetInitialTime()
     {
         return Minutes * 60f + Seconds;
     }
 
     private int GetLeftMinutes()
     {
         return Mathf.FloorToInt(m_leftTime / 60f);
     }
 
     private int GetLeftSeconds()
     {
         return Mathf.FloorToInt(m_leftTime % 60f);
     }
 }

@importguru88

First move everything from Awake() to Start(). Replace MyClock with the following

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class MyClock : MonoBehaviour
{
    public int Minutes = 0;
    public int Seconds = 0;
    private Text    m_text;
    private float   m_leftTime;

    void Start ()
    {
        m_text = GetComponent<Text>();
        m_leftTime = GetInitialTime();

        StartTimer();
    }


    IEnumerator StartTimer()
    {
        bool done = false;
        float decrementTime = 1.0f; // default yield time (one second)
        float timeLeft = m_leftTime;

	    while (timeLeft > 0)
	    {
            if (m_text != null)
            {
                m_text.text = string.Format("{0:D2}:{1:D2}", (timeLeft / 60), (timeLeft % 60));
            }
    	    yield return new WaitForSeconds(decrementTime);
            timeLeft -= decrementTime;
        }
        yield return new WaitForSeconds(0.01f); // added this just incase
    }
}

I do it like this. How would I code the Score require ?

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class ScoreManager : MonoBehaviour {
public static int score;
public Text text;

 void Start () 
 {    
     text = GetComponent <Text> ();
     score = 0;
           text.text = "Score :" + score;

 }
 

   
 {
     text.text = "Score :" + score;
 }

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class MyClock : MonoBehaviour
{
public int Minutes = 0;
public int Seconds = 0;
private Text m_text;
private float m_leftTime;

 void Start ()
 {
     m_text = GetComponent<Text>();
     m_leftTime = GetInitialTime();

     StartTimer();
 }


 IEnumerator StartTimer()
 {
     bool done = false;
     float decrementTime = 1.0f; // default yield time (one second)
     float timeLeft = m_leftTime;

     while (timeLeft > 0)
     {
         if (m_text != null)
         {
             m_text.text = string.Format("{0:D2}:{1:D2}", (timeLeft / 60), (timeLeft % 60));
         }
         yield return new WaitForSeconds(decrementTime);
         timeLeft -= decrementTime;
     }
     yield return new WaitForSeconds(0.01f); // added this just incase
 }

}