Enable USB Debugging in Developer Options on your phone.
Open up the Command Prompt and verify 'adb devices' returns a serial number.
Type 'adb reboot recovery' and when you see the little android dude with the exclamation point hold the power button and click vol up shortly.
Navigate to 'Apply update from ADB'
Open command prompt and type 'adb sideload [drag GOOGLE OTA to cmd prompt window]'
Then hit enter and it should start uploading/updating. Dragging it will automatically insert the correct path of the OTA file from wherever you downloaded it to.