Did you remove stock apps? Do You have a custom recovery?
The update patches apps instead of using the find-replace method. So if you removed the stock apps thats why it failed. If you have a custom recovery that is another reason why it failed. custom recovery blocks OTA updates. to get the updates. follow this thread. you have to go back to stock.
http://androidforums.com/ally-all-things-root/166588-how-flash-stock-lg-rom.html
the bottom of the thread also includes directions on flashing stock recovery but ONLY if you have a custom recovery (clockworkmod or Amon_RA)