Why won't my death cool down work?

I have tried all kinds of ways to make the death cool down but it won’t work. I want it so that when my player hits the ground, it takes a few seconds for the scene to be reset and also, if the player taps the screen before the death cooldown is over with, the scene with restart then. Here is my code:
float deathCooldown = 5;

bool dead = false;

public int value = 1;

public int yay = 1;

void OnCollisionEnter (Collision  col)
{
	if (col.gameObject.tag == "cup") {
		ScorePoints.score += value;

	}

	Destroy (this.gameObject);

	if (col.gameObject.tag == "Death") {
		dead = true;
		if (dead) {
			deathCooldown -= yay * Time.deltaTime;
			if (deathCooldown <= 0) {

				SceneManager.LoadScene ("Scene");
			} else {
				if (Input.GetMouseButtonDown (0)) {
					SceneManager.LoadScene ("Scene");
				}
			}
		}
	}

}

void FixedUpdate () {
	if (dead) {
		return;
	}
}

}

OnCollisionEnter only happens the instant you touch a collider. Subtracting from a countdown variable here doensn’t make much sense, as you will only decrease deathCooldown once the first time you touch something.

You unconditionally destroy the gameobject this script is attached to the instant it touches anything, so any countdown could never happen anyway.

Try removing “Destroy (this.gameObject);” from your OnCollisionEnter function, and moving all the death cooldown stuff to an update function. So something like this:

 void OnCollisionEnter (Collision  col)
 {
     if (col.gameObject.tag == "cup") {
         ScorePoints.score += value;
     }
     if (col.gameObject.tag == "Death") {
         dead = true;
     }
 }
 void FixedUpdate () {
     if (dead) {
         return;
     }
 }

void Update()
{
         if (dead) {
             deathCooldown -= yay * Time.deltaTime;
             if (deathCooldown <= 0) {
                 SceneManager.LoadScene ("Scene");
             } else {
                 if (Input.GetMouseButtonDown (0)) {
                     SceneManager.LoadScene ("Scene");
                 }
             }
         }
}