Dynamically how to make checkbox check/uncheck in angularjs controller using ng-click

I am new to Angular JS. When the user check/uncheck on a check box, I am calling a function in a controller using ng-click. I am passing $event to the function in controller. Using the $event, I am able to get the srcElement inside the controller function. Now I would like to set the previous check/uncheck value to the check box based on certain conditions.

$scope.isAccessChanged = function(event){
        if (some condition) {
            var elem = angular.element(event.srcElement);  
            /** here how to set the elem value back to whatever it was before.*/
        }
    };