If you’re seeing errors with a Mac OS X Lion (10.7.2) DMG file — corrupted download, “The disk image is corrupted,” won’t mount, or verifies then fails — this short guide walks through likely causes and fixes so you can get the installer or disk image working again.
The Fix: A "fixed" DMG usually refers to an installer where the certificate issue has been bypassed, or more commonly, a version that allows the user to perform a simple workaround. How to "Fix" the 10.7.2 Installer Yourself mac os x lion 1072 dmg file fixed
Convert the DMG
hdiutil convert /path/to/broken.dmg -format UDRW -o fixed.dmg Fixing “Mac OS X Lion 10
While many sites offer "pre-patched" or "fixed" DMGs, the safest route is downloading directly from Apple Support “The disk image is corrupted