PreBoard

PreBoard is, like springboard, an app on iOS. It initially shows the Apple logo like at boot, but is a bit brghter, it also has 4 more screens. If you reboot your iPad, iPhone, or iPod Touch while an installation in an update, PreBoard will launch and say “press home to upgrade” with a white background, and ask for your password, if you have one, If you update via iTunes, DFU, or migrate filesystems (from HFS+ to APFS) on an iOS device, it will be the same white screen, but it says press home to recover instead of press home to update. After, it takes you to a screen similar to the update screen, but it is white (no matter the device) and the bottom says “Attempting data recovery”. "When PreBoard is launched at an abnormal time, it presents a white screen and a prompt: “Press home to upgrade” (“Swipe to upgrade” on devices with no home button). This is a very indirect way of asking for authentication. When you open PreBoard and authenticate, it shows you the Apple logo (as if you were booting your device) for a second, and then it takes you to the home screen. If a shortcut was running, it continues running."