OnTriggerEnter and Exit using Position Markers? help??

So im trying to make this door open using coliders. i can open it with a button but i need to open it like this: activate the door using the button, walk into collider and door will open automatically.

im new to unity and dont understand what im doing wrong, can someone help!

using UnityEngine; using System.Collections;

 public class AutobotDoor : MonoBehaviour 
 {
     //Components
     Animator doorAnim;
     //Refrences
     public GameObject lightObj;
     Light light;
     Renderer lightRend;
     public Transform platform;
     public Transform[] posArr;
     public int targetPos;
     public float speed = 5f;
 
     void Start () 
     {
         //Get Component
         doorAnim = this.GetComponent<Animator>(); 
     }
     
         void OnTriggerEnter(Collider otherCol)
         {
         //check if the player emetered the trigger
         if(otherCol.tag == "Player")
         {
             //DoStuff
             platform.position = Vector3.MoveTowards(platform.position, posArr[targetPos].position, speed * Time.deltaTime);("DoorState" , true);
         }
 
         }    
 
         void OnTriggerExit(Collider otherCol)
         {
         //check if the player emetered the trigger
         if(otherCol.tag == "Player")
         {
             //DoStuff
             platform.position = Vector3.MoveTowards(platform.position, posArr[targetPos].position, speed * Time.deltaTime);("DoorState" , false);
         }
 
         }
 x
         void OpenDoor()
         {
             // 1) Check current state of targetPos and change it
             if(targetPos == 0)
             targetPos = 1;
             else
             targetPos = 0;
         }
 
     void Update () 
     {
     
     }
 }