Before you do step change the package name, you must do this step for firebase project configuration
Make sure you already change applicationId file app/build.grade.by follow link below
app/build.grade.
Please DON'T change any dependencies { } version and gradle version, it may cause error
Please follow this step to configure firebase on android
Configure Firebase for Androidarrow-up-right : http://blog.dream-space.web.id/?p=217arrow-up-right