I've never tried it that way so don't know if it will work. I'm sensing there may be a problem because when you plug in the sat box it automatically looks for a sat signal. There have been times when I've had an issue with my sat signal and upon plugging the box back in it still couldn't find the signal and would not let me get to the recorded programs in "My Recordings".
You might want to try it at home by unplugging the box and then disconnecting the antenna. Plug the box back in after 10 minutes and see what happens. Also disconnect the phone line and or internet if you have it connected to the box.