How to programmatically uncheck/check checkbox in angularjs latest version (1.4.0-beta.5)?

This is the code in jsfiddle using version 1.1.1. This is the working code by the way. What it does is uncheck the checkbox if the button is clicked.

https://jsfiddle.net/j2a53gwj/2/

I have the same exact code but the angularjs version is 1.4.0-beta.5. http://plnkr.co/edit/hUE2xSI8PCads8WOumLx?p=streamer

angular.module("CheckAllModule", [])
    .controller("checkboxController", function ($scope) {


     $scope.clickme = function() {
      alert("x");
      $scope.master = false;
      //$scope.ss.Selected = false;
    };

  });

The code isnt working in this version.

I know, I have already asked this question before, but because of the version upgrade, the code didn't work which makes my question valid.

How will I do it in angularjs latest version? or if the version is not the problem, then what is? I did copy paste the code so that I know I'm using the same code only with different versions.