It looks like Apple has pulled the update (for that model, perhaps). Here are steps to proceed until an update to the update is released:
Thanks to The Loop for the details on this:
Sooner than I expected a new build is out:
iPad 2 users can update to the new firmware update by plugging their iPad into iTunes if itxe2x80x99s in a bricked state or by heading into Settings and navigating to the software update menu and updating like they normally would.