How to unlock hard drive?
Trying to install OSX and hard drive is locked. How do I unlock it?
MacBook Pro, Mac OS X (10.7.4)
Fix Permissions for a Locked Drive
Open Terminal in the Utilities folder. Paste the following commands at the prompt. Press RETURN after each. The first command will prompt for you to enter your admin password. It will not be echoed to the screen. After entering your password press RETURN again.
sudo chflags 0 /Volumes/*
sudo chmod a+rx /Volumes/*
killall Finder
An alternative is to download BatChmod and use it to fix the permissions.
The above may help you out.