Issue: You have a custom recovery installed and your LG G2 prompts you to install the new OTA (i.e. KitKat update). You then accidentally/unknowing of consequences accept the update. Your phone restarts and keeps going to the custom recovery which you had installed, instead of booting to the update. You endlessly try to boot to your phone, but it just keeps going back to your custom recovery.
Things to do ahead:
1. Have LG G2 drivers installed on computer you will be using. You can get those from the LG website easily by searching LG G2.
2. Obtain ADB and fastboot files from HERE
3. Obtain working TWRP vs 2.7.0 from HERE if you don't have the TWRP recovery installed (i.e. if you're using CWM or Philz recovery).
1. If you have TWRP recovery installed, proceed from step 9
2. If you have CWM or Philz recovery installed, follow these next steps.
3. When inside CWM/Philz recovery, click on option to install zip.
4. Have your phone connected to a computer which has the LG G2 drivers installed, found on LG's site. Make sure to install drivers without phone connected to computer first. After installing, restart computer, and then plug phone to computer USB port.
5. Now that you have the phone plugged to comp, and that the comp has recognized your phone, open up CMD and navigate to the folder where you have your ADB file located and workable TWRP recovery zip file.
6. Once there, click on install using sideload on your phone's custom recovery which should be located inside the install zip option.
7. Then type in CMD on computer this: ADB sideload TWRP-file-name.zip
Note. Replace TWRP-file-name.zip with whatever the TWRP zip file on your computer is named to the letter.
8. Your phone will install TWRP recovery at this point. Once it finishes, restart your phone by rebooting recovery (should be an option somewhere there in the main level of the recovery)
9. TWRP should boot now. Once inside TWRP, click on Advance
10. Then click on Terminal Command
11. Next click on Select
Note: Do not navigate to any other folder. Just click on Select. You'll know what I mean once your in Terminal Command.
11. Type this command in the space provided in your phone (NOT in CMD) which should be now in Terminal Command mode exactly to the last letter. I'm not kidding; don't miss a character or replace a number. You risk nuking your phone. Double check your typing.
Type this: dd if=/dev/zero of=/dev/block/platform/msm_sdcc.1/by-name/fota
Note: You should note that there is a space between dd and if=/dev, and another space between /zero and of=/dev
12. Once the command finishes running, about 30 seconds or less, restart phone. And voila. Your phone should boot back to your pre-selecting update with OTA mode.
In my case, I wiped everything and tried restoring one of my nandroids. That did not help me boot my phone. However, when I did the above mentioned steps, my phone booted to my backed up state which I installed prior.
Hopefully you don't end up being a victim of this. But if you are, now you can confidently bring yourself back
Good luck and share your progress. Thanks!