If you have FRF50 try this http://www.androidpolice.com/2010/06/23/latest-nexus-one-froyo-rom-leak-frf83/ http://www.androidpolice.com/2010/06/23/latest-nexus-o

If you have FRF50 try this http://www.androidpolice.com/2010/06/23/latest-nexus-one-froyo-rom-leak-frf83/ http://www.androidpolice.com/2010/06/23/latest-nexus-one-fro... edit: BobbyPhoenix (check link above) claims that if you have FRF72 you can flash back to FRF50 and then apply FRF83 and it will work.