Best Answer OldBaldy , 15 April 2013 - 01:25 AM
It's meant to protect root through an update, but if you leave su protected, a nandroid restore cannot overwrite it, leaving you with an incomplete system restore, thus the black screen. If you did not have su protected, then you possibly just have a bad backup. Either way, Matt's utility for JB it's the quickest way back.
Sent from my DROID RAZR
Go to the full post