onpopstate and pushstate not working - can't spot why

Question

This is not a duplicate question, I cannot find the help I need. I would appreciate advice as to why my following code is not working please.

  window.addEventListener("popstate", () => {
  if (!cookieExists()) {
    showAlerts();
    countDownTimer();
    document.cookie = `${cookieName}=true;max-age=604800;SameSite=None; Secure`;
  }
});

window.history.pushState({}, "", "/");

For context, when the user hits the browser back button, my alerts should show.

Edit: I have updated my code and it still doesn't work. When I click back, it just goes back to the previous page. When I refresh I get an 'oops something went wrong' is there a way to test in the console?