LG Flashtool is a simple app created by LG which help you to flash firmwares in LG devices in a faster way than before. The process is much easier than using fastboot flashing process. It is also good because you don’t need to unlock the bootloader. It locks bootloader and resets tamper flag.
LG Flashtool has a few disadvantages. It changes the factory version of the device. If you flash a firmware that has a different factory version, then even the device factory version changes. If you want to have the original device factory version, download the tool here. It will backup the device factory version to /sdcard/version.txt. Then copy the text file to your PC. Below there is a tutorial which tells you how to restore your device version.
Also Read: Best Custom ROMs for LG G3 (Fast & Stable)
Carefully follow the steps below and learn how to flash stock factory images on your LG device.
If you are doing this for the first time you have to make some preparations. Follow the steps below.
- Download and install the LG drivers, here.
- Download and install LG flashtool, here.
- Create a folder where to put the DLL and the Firmware file.
- Download DLL file, D820 North America Version. D821 Global Version. Place the file you downloaded to created folder.
- Download firmware D820, D821. Place TOT file to folder that you created.
- Turn off the phone.
- Hold down volume_up key then connect USB cable.
- Reboot in download mode.
- Let Windows install drivers.
- Change port number to 4.1. Go to device manager and find LGE Mobile USB Serial Port (COMxx) (where xx is the port number). Click on Properties > Port Settings > Advance > Change COM Port Number to COM41.
If you don’t want to flash any firmware yet just press the power key for 10 seconds and the phone will turn on.
- Reboot your phone in download mode.
- Open LG Flashtool.
- If Model Config window does not start, then click on the sign with two cogwheels.
- Check the box next to Select Manual Mode.
- Click on “…” and select the DLL file for your your phone.
- Click on Add and add the TOT file.
- Click OK.
Click on the yellow arrow sign to start flashing. If you see READY, then reconnect your phone. Then “Waiting for Connection” text will appear in the COM41 window. When it goes to 80% the phone will shut down so don’t be scared. After finishing the LED on your phone will start blinking green. It’s time to disconnect the USB cable. Wait until the green light stops and then turn on your phone.
Restore Device Factory Version
At first create a text file and name it version.txt. Paste the device factory version from the log file which is located in LOG folder where are DLL and TOT files. Download this tool.zip for restoring your device version here. Flash tool.zip in recovery.