Enemy Can't Take Damage!!!

HI I'm starting my first real RPG and I made a script for the battle system but enemies can't take any damage! Here's my script:

 using UnityEngine;
 using System.Collections;
 
 public class Player : MonoBehaviour {
 
     public int rand;
     public int hp;
     public int luck;
     public int enemyId;
     public bool battle;
     public bool myTurn;
     public int enemyHP;
     public int enemyAttack;
     public bool blocking;
     public bool enemyBlocking;
 
     void Start () {
     
     }
 
     void Update () {
         //Battles and Enemys
         if (enemyId == 0) {
             battle = false;
         }
         if (enemyId > 0) {
             battle = true;
         }
         if (battle == true) {
             myTurn = true;
             //ADD BATTLE UI LATER
             if (myTurn == true){
                 //MY ATTACKS
                 if (Input.GetKeyDown(KeyCode.Alpha1)){
                     if (enemyBlocking == false){
                         rand = Random.Range(1, 100);
                         if (rand <= luck){
                             enemyHP = enemyHP - 20;
                         } else {
                             enemyHP = enemyHP - 5;
                             myTurn = false;
                         }
                     } 
                     if (enemyBlocking == true){
                         enemyBlocking = false;
                         myTurn = false;
                     }
                 }
             }
         }
         if (enemyId == 1) {
             enemyHP = 30;
              if (myTurn == false){
                 enemyAttack = Random.Range(1, 4);
                     if (enemyAttack <= 3){
                         if (blocking == false){
                             hp = hp - 4;
                     } if (blocking == true) {
                         blocking = false;
                     }
                 }
                 if (enemyAttack == 4){
                     enemyBlocking = true;
                 }
             }
         }
     }
 
     void OnCollisionEnter2D (Collision2D coll){
         //Enemy ID's / Enemy Collisions
         if (coll.gameObject.name == "Test Enemy") {
             enemyId = 1;
         }
     }
 }
 

If you can help me that would be great! I think is has to do with where I set the enemy HP.

EDIT: Also colliding with an enemy isn't working so I have been modifying the enemy ID in the inspector to start a battle. With the enemy it's self it will just disappear after a while (not in a battle).