How to open and close a door

I'm making some kind of a door script but it's not working, I've tried with both Lerp and Slerp but it just jumps to that location and doesn't come back. Can you help?

 using System.Collections;
 using UnityEngine;
 
 public class Door : MonoBehaviour
 {
     public Transform fpsCam;
 
     Vector3 startPos = new Vector3();
     Vector3 endPos = new Vector3();
 
     bool canOpen = true;
 
     void Start()
     {
         startPos = transform.position;
         endPos = startPos + Vector3.up * 15;
     }
 
     void OnMouseDown()
     {
         if(canOpen && Vector3.Distance(transform.position, fpsCam.position) > 5f)
             return;
         transform.position = Vector3.Lerp(transform.position, endPos, 0.5f);
         canOpen = false;
         StartCoroutine(GoDown());
     }
 
     IEnumerator GoDown()
     {
         yield return new WaitForSeconds(3.5f);
         transform.position = Vector3.Lerp(transform.position, startPos, 0.5f);
         canOpen = true;
     }
 }