Pause menu not working

Ok, I had a crappy pause menu script that worked but was terrible, after the last couple Unity updates that pause menu broke and the buttions don't work anymore. So I decided it was as good a time as any to make a new one.

Problem is nothing I do works, the main menu button won't load the main menu. The buttons are linked correctly they just don't work. I click on them and nothing happens. In the current script i'm using it has a Resume game function which I don't really care for and would rather have a quit game button like my old menu.

Other issues with the pause menu is it won't lock the camera in place and when I close the pause menu by hitting escape the cursor lingers and you need to click to re-hid and lock it.

So to sum up the problems i'm having are

1. Buttons won't work no matter what I do

   1. Camera won't lock in place when paused

   2. cursor won't hide and lock after closing pause menu until you click

My understanding of scripting in basic so I can tinker with scripts but have a hard time writing them. Any help to fix this script or recommend a better one would be greatly appreciated. Again I also want to replace the Resume function with a quit game function because their is no point having a resume button when escape is just the resume button.

Here is the script i'm currently using

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.SceneManagement;
 
 public class MenuController : MonoBehaviour
 {
     public string mainMenuScene;   
     public GameObject pauseMenu;
     public bool isPaused;
 
     //Use this for initialization
     private void Start()
     {
 
     }
 
     // Update is called once per frame
     void Update()
     {
         if (Input.GetKeyDown(KeyCode.Escape))
         {
             if (isPaused)
             {
                 Resume();
             }
             else
             {
                 isPaused = (true);
                 pauseMenu.SetActive(true);
                 Time.timeScale = 0f;
             }
         }
     }
 
     public void Resume()
     {
         isPaused = false;
         pauseMenu.SetActive(false);
         Time.timeScale = 1f;
     }
 
     public void ReturnToMain()
     {
         Time.timeScale = 1f;
         SceneManager.LoadScene(mainMenuScene);
     }
 }