Get() and Set() values of a gridArray from another scipt

Good day, I am very new to Unity, and I'm making an application that simulates a breadboard based on collisions. I have a GridMap script connected to my Grid. It contains a two-dimensional gridArray on it, as well as Getters and Setters. I looks something like this:

 public class GridMap : MonoBehaviour
 {
     public int width;
     public int height;
     public int[,] gridArray;
 }
  
 public void Start()
     {
         Init(20, 63); //The size of my grid
     }
  
 public void Init(int width, int height)
     {
         this.width = width;
         this.height = height;
         gridArray = new int[width, height];
         for (int x = 0; x < gridArray.GetLength(0); x++)
         {
             for (int z = 0; z < gridArray.GetLength(1); z++)
             {
                 //DoSomething
             }
         }
     }
  
 public int Get(int x, int z)
     {
         if (CheckPosition(x, z) == 0) //outofbounds error detection
         {
             return 0;
         }
         return gridArray[x, z];
     }
  
 public void Set(int x, int z, int value)
     {
         if(CheckPosition(x,z) == 0) //outofbounds error detection
         {
             return;
         }
         gridArray[x, z] = value;
     }

I also have a script on another object called BreadboardLogic which acts as a listener for Collisions, then detects what cellPositions those Collisions occured at. Its main method looks like this:

 private void OnCollisionEnter(Collision collision)
     {
         Collider collider = collision.GetContact(0).thisCollider;
         collisionPoint = collision.GetContact(0).point;
         cellPosition = grid.WorldToCell(collisionPoint);
         Debug.Log(cellPosition);
         Debug.Log(collision.GetContact(0).otherCollider);
     }

With this, I am able to detect the Vector3Int cellPositions of the collisions and print it on Debug, however I would like use them to Set() the value of those respective grid positions to 1 on my gridArray. What would be the best way to do this? I first assumed it was something like this:

 gridMap.Set(cellPosition.x, cellPosition.y, 1);

But it doesn't work T_T Any ideas would be appreciated, thanks in advance!