I have a paid iPhone Developer account with beta 8 of the firmware installed. Now that I'm selling my iPhone, I need to downgrade it to 1.1.4 and unlock it.

The problem is that I'm unable to restore 1.1.4 through iTunes 7.7. I get a error code of 20?? I also tried restoring through XCode Organizer and that didn't work either. Getting into recovery mode is as far as I can get...

Any ideas?? The auction ends in 5 days!