Check if user exists and store his data with Firebase+Angular+Facebook

I have a Facebook signup method and i want it to check if the user is already persists in my Firebase. If it is, i'd like to set this data to $rootScope.loggedInUser to share across controllers.

Here's the implementation of this idea. The problem is — no data written to firebase as well as no redirection performed. It seems that i miss something obvious. Any ideas?

Firebase v2.0.4

AngularFire 0.9.0

Angular 1.2.20

  $scope.loginFacebook = function() {
                $scope.auth.$authWithOAuthPopup("facebook")
                    .then(function(authData) {
                        var userId = authData.uid

                        function checkIfUserExists(userId) {
                          (new Firebase(USERS)).child(authData.uid).once('value', function(snapshot) {
                            var exists = (snapshot.val() !== null);
                            userExistsCallback(userId, exists);
                          });
                        }    

                        function userExistsCallback(exists) {
                          if (exists) {
                            var loggedInUser = $firebase(new Firebase(USERS).child(authData.uid)).$asObject();
                            loggedInUser.$loaded().then(function() {
                              $rootScope.loggedInUser = loggedInUser;
                              $window.location.href = '#/profile';
                            });
                          } else {  
                            $firebase(new Firebase(USERS).child(authData.uid))
                                .$update({
                                    "uid": authData.uid,
                                    "email": authData.facebook.email,
                                    "displayName": authData.facebook.displayName,
                                    "image": authData.facebook.cachedUserProfile.picture.data.url
                                })
                                .then(function(authData) {
                                    $rootScope.loggedInUser = {
                                        'uid': authData.uid,
                                        'email': authData.facebook.email,
                                        'displayName': authData.facebook.displayName,
                                        'image': authData.facebook.cachedUserProfile.picture.data.url
                                    }
                                    var loggedInUser = $firebase(new Firebase(USERS).child(authData.uid))
                                    $rootScope.loggedInUser = loggedInUser.$asObject();
                                    $window.location.href = '#/profile';
                                });
                          }                        
                    }
                }).catch(function(error) {
                    console.error("Authentication failed:", error);
                });
            }