1. Download Stock Rom LG G3 (LG AS990 BRIGHTPOINT).
• This Stock is KDZ file, remember to copy this KDZ file into LG Flash Tool 2014 folder
• Check the firmware that match with your phone version, for , below

• LG KDZ Firmware

  No.	Model	Suffix	Version	Buyer	Buyer Name	Download
  1.	LG AS990	ABPTTN	AS99021A_00	BPT	BRIGHTPOINT	Download
  2.	LG AS990	ABPTTN	AS99020A_01	BPT	BRIGHTPOINT	Download


2. Download Driver LG: Here
3. Latest LG FlashTool : Here

1. Make sure you have download all requirement tool above
2. Then Install the drivers with your phone connected with your Computer, when it finished disconnect your LG G3 (LG AS990 BRIGHTPOINT) phone from your computer.
3. Now turn your LG G3 (LG AS990 BRIGHTPOINT) phone off, then continuously click on the volume up button and connect your phone to your PC, 
4. Now, enter your LG G3 (LG AS990 BRIGHTPOINT) into download mode.  ( visit this guide or see at the end of this post)
5. Run LGFlashTool2014.exe.
6. If you cannot run LGFlashToo2014.exe, You must install Visual C++ Runtime Library, get here
7. There are two options to flash your LG G3 (LG AS990 BRIGHTPOINT) .
• Normal Flash : You can select this option if you want Flash ROM without losing any data. Only use this when you need to fix system error.
• CSE Flash : You can choose this option when you need a fresh format. All data will be deleted. Its suitable for upgrading or downgrading ROM or simply use this when you need to back to Stock. 

  LG flash tool normal flash / CSE flash



8. Select Type: CDMA
9. PhoneMode: DIAG
10. Select KDZ file : browse your KDZ file in your drive
11. Then you can Click on Normal Flash or CSE Flash (see step 7 to decide this option)
12. Then click Start.

    LG flash tool - start

13. Then click on Clear Phone Software update registry.

    Lg flash tool - Clear Phone Software update registry.

14. No need to choose desired language, it automatically change to English as a default setting.
15. Finally you can click OK.
16. You must wait a minute for the LG Mobile Support tool to recognize the LG G3 (LG AS990 BRIGHTPOINT)  device.
17. When you wait this process, may take 5 minute the tool to recognize it.
18. The software will start the extraction on your device.
19. When the process reach 100% your LG G3 (LG AS990 BRIGHTPOINT)  will reboot.
20. Then, you must Unplug your LG G3 (LG AS990 BRIGHTPOINT)  from your computer by remove USB Cable from it.,
21. Finish,

If #1 method is failed to flash your LG Android device, you can use this second method, flashing LG device using R&D Test Tool