Jump Not Working

So im following this tutorial and am on the part where he adds in the jumping part. I created the ground check game object and placed it right but if is spam the space bar it just keeps jumping. I think the problem is with the ground parameter as even if i am in the air it is still checked on. Any help. Thanks. Here is the Controller code:

 using UnityEngine;
 using System.Collections;
 
 public class RobotController : MonoBehaviour {
     //This will be our maximum speed as we will always be multiplying by 1
     public float maxSpeed = 2f;
     //a boolean value to represent whether we are facing left or not
     bool facingLeft = true;
     //a value to represent our Animator
     Animator anim;
     //to check ground and to have a jumpforce we can change in the editor
     bool grounded = false;
     public Transform groundCheck;
     float groundRadius = 0.2f;
     public LayerMask whatIsGround;
     public float jumpForce = 700f;
     
     // Use this for initialization
     void Start () {
         //set anim to our animator
         anim = GetComponent <Animator>();
         
     }
     
     
     void FixedUpdate () {
         //set our vSpeed
         anim.SetFloat ("vSpeed", rigidbody2D.velocity.y);
         //set our grounded bool
         grounded = Physics2D.OverlapCircle (groundCheck.position, groundRadius, whatIsGround);
         //set ground in our Animator to match grounded
         anim.SetBool ("Ground", grounded);
         
         
         float move = Input.GetAxis ("Horizontal");//Gives us of one if we are moving via the arrow keys
         //move our Players rigidbody
         rigidbody2D.velocity = new Vector3 (move * maxSpeed, rigidbody2D.velocity.y);    
         //set our speed
         anim.SetFloat ("Speed",Mathf.Abs (move));
         //if we are moving left but not facing left flip, and vice versa
         if (move < 0 && !facingLeft) {
             
             Flip ();
         } else if (move > 0 && facingLeft) {
             Flip ();
         }
     }
     
     void Update(){
         //if we are on the ground and the space bar was pressed, change our ground state and add an upward force
         if(grounded && Input.GetKeyDown (KeyCode.Space)){
             anim.SetBool("Ground",false);
             rigidbody2D.AddForce (new Vector2(0,jumpForce));
         }
         
         
     }
     
     //flip if needed
     void Flip(){
         facingLeft = !facingLeft;
         Vector3 theScale = transform.localScale;
         theScale.x *= -1;
         transform.localScale = theScale;
     }
 }