Ionic update

I am not able to display the back button, its not working.
I am using ionic - 0.9.27

few minutes back it was working, then i tried to upgrade my library to beta version, there i was seeing lot of errors, so I switched back to .27 using bower.

Now the back button is not working.

Also i am not able to inject $ionicNavBarDelegate service, it throws Unknown provider: $ionicNavBarDelegateProvider <- $ionicNavBarDelegate HElp me

Can you put together a codepen? There have been a lot of changes in the framework since 0.9.27, so be prepared for that