Turn on canvas on trigger

Hey I’m trying to create like a call of duty sprite. Where a character goes on top of the bomb and then it automatically enables the canvas to turn on. I have enabled for a user to step on bomb then he is carrying it thus removing the bomb from scene but hopefully not totally from the environment, if that makes any sense. I have disabled this “bomb” sprite from the beginning so it wont show up automatically. But my code keeps crashing saying, “Object reference not set to an instance of an object”

heres my code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine.UI;
using UnityEngine;

public class PickUpBomb : MonoBehaviour {

   private int count = 0;
   GameObject go;

   private void Start()
   {
      GameObject go = GameObject.Find("BombCanvas");

   }


   void OnTriggerEnter(Collider other)
   {
      if (other.gameObject.CompareTag("Pick Up"))
      {
         other.gameObject.SetActive(false);
         count = count + 1;

         go.SetActive(true);

      }

   }

you could try go.enabled = true/false/!go.enabled