Upgrading to AppleTV software 3.0.2 w/ external USB drive

I use a 1TB external USB as my primary drive. I accidentally upgraded the ATV to 3.0.2 without changing the internal hard drive to primary. Now my ATV will not work. I have a blank screen after restart with and without the external connected. Do I need to do a factory reset of the ATV and then reinstall aTV Flash or is there an easier way to recover from my mistake?