Slerp rotation on collision - C#

Hi all,

I'm having trouble with rotation on collision. Firstly, let me write what I'm trying to accomplish. I have an enemy (right now just a cube) that "wanders" around. When he hits a wall, I have him rotate but that part isn't working. When he hits the wall I would like it to rotate a random degrees and then continue moving. Currently he will hit the wall, rotate a few degrees and then keep going - like the rotation didn't have time to finish. Problem is with this setup, he will just drag along the wall because he didn't fully rotate in another direction.

So it's worth pointing out that the movement works fine. He hits the wall and I know this part is successful because the console reads that it hit the wall like I ask it to on the collision function. Its just the rotation part that doesn't work. Any suggestions?

Here is the code - or at least the important parts:

using System.Collections;

public class RotateOnCollisiont : MonoBehaviour {

 public float smooth = 2.0f;
 public float wanderSpeed;
 
 public bool wander;
 
 Vector3 wanderDirection;
 
 void Start () {        
     wander = true;
 }

 void Update()
 {
     Wander();
 }

 void Wander()
 {
     if (wander == true)
     {
         float wanderMovement = wanderSpeed * Time.deltaTime;
         
         wanderDirection = transform.position;
         
         rigidbody.velocity = transform.forward * wanderMovement;
         
         transform.LookAt(wanderDirection);

     }
 }
 void OnCollisionEnter(Collision collision)
 {
     if (collision.collider.tag == "Wall" && wander == true)
     {
         Debug.Log ("We hit a wall");
         wander = false;
         ChangeDirection();

     }
 }

 void ChangeDirection()
 {
 // Please note I only need it to rotate around the y axis:
     Quaternion target = Quaternion.Euler(0, Random.Range(45.0f, 270.0f), 0);
     transform.rotation = Quaternion.Slerp(transform.rotation, target, Time.deltaTime * smooth);
     wander = true;
     
 }

}