Lerp help desperately needed.

I have a lerp script that I have attached to a button on the bottom of a lift shaft, which takes the lift up to a certain point. works perfectly.. What I want is a lerp script that I can apply to a button at the top to take the lift back down again to the start point. This is for VR interaction...below is lerp for going up.

Any help would be really greatly appreciated. using System.Collections; using System.Collections.Generic; using UnityEngine;

 public class Lerp : MonoBehaviour
 {
     public GameObject MovingCube;
     private Vector3 startPos;
     private Vector3 endPos;
     private float distance = 4.19f;
     private float lerpTime = 10;
     private float currentLerpTime = 0;
     // Start is called before the first frame update
     void Start()
     {
         startPos = MovingCube.transform.position;
         endPos = MovingCube.transform.position + Vector3.up * distance;
         
     }
 
     // Update is called once per frame
     private void OnTriggerStay(Collider other)
     {
         if (other.CompareTag("Finger"))
         {
             currentLerpTime += Time.deltaTime;
             if (currentLerpTime >= lerpTime){
                 currentLerpTime = lerpTime;
             }
 
             float Perc = currentLerpTime/lerpTime;
             MovingCube.transform.position = Vector3.Lerp(startPos, endPos, Perc);
         }
     }
 
    
 }