Device Firmware Upgrade (DFU) mode

A mode in which a device’s Boot ROM code waits to be recovered over USB. The screen is black when in DFU mode, but upon connecting to a computer running iTunes or the Finder, the following prompt is presented: “iTunes (or the Finder) has detected an (iPad, iPhone, or iPod touch) in Recovery mode. The user must restore this (iPad, iPhone, or iPod touch) before it can be used with iTunes (or the Finder).”