Восстановление interval-а по нажатию на кнопку

let colors = ["green", "red", "blue", "black"]; 
let div = document.getElementsByTagName('div'); 
let buttons = document.querySelectorAll('button'); 
let x = -1; 
let y = 2000; 
 
let changeColors = setInterval(function() { 
    x += 1; 
    div[0].style.backgroundColor = colors[x]; 
    if (x === colors.length) { 
        x = -1; 
    } 
}, 2000) 
 
buttons[0].addEventListener('click', function() { 
    clearInterval(changeColors); 
    changeColors = null; 
}) 
 
buttons[1].addEventListener('click', function() { 
    if (changeColors === null) { 
        let changeColors = setInterval(function() { 
            x += 1; 
            div[0].style.gackgroundColor = colors[x]; 
            if (x === colors.length) { 
                x = -1; 
            } 
            buttons[0].addEventListener('click', function() { 
                clearInterval(changeColors)	 
            }); 
        }, 2000) 
    }; 
}) 
    

div { 
  width: 150px; 
  height: 150px; 
  border-radius: 50%; 
  background-color: red; 
}

<div></div> 
<button>Clear Interval</button> 
<button>Return Interval</button>