Unity freezes every time I run one specific scene

I have different scenes that work fine except when I reach one specific scene. The different thing about this scene is the scripts. A game manager script and a card script. (The game is a personnalized memory game based on the memory card game). Every time I reach that scene, Unity freezes and I can’t play it nor load another scene (using a loadonclick script). I am new to Unity and this is the first real problem I found. Especially when this same scene used to work fine when I first finished it yesterday… Anyway, here is the script I am currently using

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

public class CardScript : MonoBehaviour {

public static bool DO_NOT = false; 

[SerializeField]
private int _state;
[SerializeField]
private int _cardValue;
private bool _initialized = false;

private Sprite _cardBack;
private Sprite _cardFace;
private GameObject _manager;

void Start() {
    _state = 1;
    _manager = GameObject.FindGameObjectWithTag("Manager");

}

public void setUpGraphics() {
    _cardBack = _manager.GetComponent<GameManager>().getCardBack();
    _cardFace = _manager.GetComponent<GameManager>().getCardFace(_cardValue);

    flipCard();
}

public void flipCard() {

    if (_state == 0)
        _state = 1;
    else if (_state == 1)
        _state = 0;

    if (_state == 0 && !DO_NOT)
        GetComponent<Image> ().sprite = _cardBack;
    else if (_state == 1 && !DO_NOT)
        GetComponent<Image> ().sprite = _cardFace;
}

public int cardValue {
    get { return _cardValue; }
    set { _cardValue = value; }
}
//50
public int state {
    get { return _state; }
    set { _state = value; }
}

public bool initialized {
    get { return _initialized; }
    set { _initialized = value; }
}

public void falseCheck() {
    StartCoroutine(pause());
}

IEnumerator pause() {
    yield return new WaitForSeconds(1);
    if (_state == 0)
        GetComponent<Image>().sprite = _cardBack;
    else if (_state == 1)
        GetComponent<Image>().sprite = _cardFace;
    DO_NOT = false;
}

}

The part that I changed a lot lately was the flipcard part because I had some trouble getting it to work, so I’m guessing the problem could be coming from there?

Solved: The problem was inside the 2nd for loop. i was set from 0 to 7 covering 12 cards whereas in my scene, I had changed it to 16 and forgot to modify the range of i in the script from 0 to 9.