How to restore iPhone when stuck in recovery mode

The iPhone when installing an iOS update gets often stuck in recovery mode. Essentially, you'll find that your device won't turn on, or it will cycle the boot process but never reach the home screen. You might even see the iTunes logo with a USB cable pointing at it on your screen.

Tip: When your iPhone is stuck in recovery mode, do not click Recover in iTunes, this will erase all your data.

To get your iPhone out of recovery mode, do the following:
1. Connect your iPhone with a USB cable to your PC.
2. Download RecBoot for Mac or Windows and install it on your Mac or PC.
3. Launch RecBoot. A window appears.

4. Click on Exit Recovery Mode. Voilà!

RecBoot is a free utility for Windows and Mac which allows you, to kick the connected device(s) into and out of recovery mode. It requires .NET Framework v4.0, LibUSB (only if you want recovery detection, otherwise not needed) and iTunes 9.2 or later.
RecBoot does not work on 64-bit PCs. So, do NOT use on 64-bit PCs!