I released an update for my App and it was approved. It was approve despite the fact that it included a serious localization bug where most users are getting the wrong language.
it is not possible to revert the app version. you should upload the previous version as new version again to fix this.
one thing you can do is : "Expediting an App Review"
please check the following link.
https://developer.apple.com/appstore/contact/?topic=expedite
thanks