I had the same exact problem, you in fact do have to update your system from 2.1 for you to be able to inject fbi

Actually you can inject it on any firmware but the files provided in the guide are for the latest firmware. You can make your own files with Universal Inject Generator (or my helper tool...)I had the same exact problem, you in fact do have to update your system from 2.1 for you to be able to inject fbi