MouseLook Disable function

I am trying to disable the MouseLook when the left mouse button is clicked. However the code I have put in does not do that and I am not quite sure why. Any help would be greatly appreciated. Here is the code:`

class MouseLook : MonoBehaviour {

public enum RotationAxes { MouseXAndY = 0, MouseX = 1, MouseY = 2 }
public RotationAxes axes = RotationAxes.MouseXAndY;
public float sensitivityX = 15F;
public float sensitivityY = 15F;

public float minimumX = -360F;
public float maximumX = 360F;

public float minimumY = -60F;
public float maximumY = 60F;

float rotationY = 0F;

void Update ()
{

	if (Input.GetMouseButtonDown (0) = false) {

	if (axes == RotationAxes.MouseXAndY)
	{
		float rotationX = transform.localEulerAngles.y + Input.GetAxis("Mouse X") * sensitivityX;
		
		rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
		rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);
		
		transform.localEulerAngles = new Vector3(-rotationY, rotationX, 0);
	}
	else if (axes == RotationAxes.MouseX)
	{
		transform.Rotate(0, Input.GetAxis("Mouse X") * sensitivityX, 0);
	}
	else
	{
		rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
		rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);
		
		transform.localEulerAngles = new Vector3(-rotationY, transform.localEulerAngles.y, 0);
	}
	}else if (Input.GetMouseButtonDown (0) = true) {

	}
}

void Start ()
{
	// Make the rigid body not change rotation
	if (GetComponent<Rigidbody>())
		GetComponent<Rigidbody>().freezeRotation = true;
}

}
`

You are using ‘=’ instead of ‘==’ on line 17. Plus using ‘!’ is more professional:

 if (!Input.GetMouseButtonDown (0)) {