If you own an LG phone, you'll definitely be interested in LG Mobile Support Tool. This tool can be handy if there's any kind of flaw during a software update and you can't get your device to boot.
The software for an emergency recovery
This program will help you to reinstall your handset's software but, for such purpose, you'll have to enable your phone's emergency mode. Once you've done so, and the program has detected it, you'll have several different options to recover the system. Remember that you'll have to provide both your model and number series or device IMEI, so don't forget to have all that information at hand.
Mobile Support Tool will take care of all the rest and you'll simply have to be patient enough for the process to be completed, which will take more or less time depending on the size of the software image you're downloading. Don't unplug the USB cable until it's all finished.