I need to factory reset my glalaxy nexus by google. It does not have a sim card but im not sure if that matters. i have been looking on the internet and have found videos explaining that if i hold down both of the volume buttons and the power button that it will bring up a menu which it did. then it explained that if i select the recovery mode option that a little android person w3ill come up with an exmlation mark and it did but when id does that it says no command. what do i do?