Originally Posted by sfhub
I would try it over again a few times.
There appears to be some units that may have corrupted eMMC which is probably responsible for the pause. Sometimes these can get blocked out automatically by the eMMC firmware.
Got a brand new Nexus 7 here, about 2 weeks old. I let it sit charging about a week with no use. Tried to start it, it wouldn't start. Held power and vol up to reboot it. Long story short, I have the exact same issue as the original poster. It will not unlock. I can get to the screen to unlock it. But when choosing unlock bootloader -> yes, it just hangs forever. I spent hours on this over the weekend with no success, various restore programs. At one point, it did manage to reboot to the Google startup screen with the unlocked padlock. Not sure if that means it's unlocked. But it then got stuck.
Also, I've seen all sorts of error messages referring to e:\ and missing folders.
Is this thing trashed?