The LG P970 Optimus Black is a legacy device, and performing a firmware update today generally requires using a KDZ flasher tool rather than standard over-the-air (OTA) updates
Because LG’s official methods were so unreliable, the hacking community (XDA Developers) created a savior: SmartFlash Tool for P970. This was the definitive way to perform a firmware change. firmware+change+update+on+lg+p970+optimus+black
Before touching the software of your device, you must take these precautions to avoid "bricking" (permanently disabling) your phone: The LG P970 Optimus Black is a legacy
Launch the Flasher Tool: Open the flasher software from its directory on your PC. firmware+change+update+on+lg+p970+optimus+black
Preparations
LG P970: Upgrading to Android 4.0.4 and Rooting - Hypn.za.net 29 Apr 2013 —