Use TowelRoot app instead! It is oneclick and without reboot.
Starting fom 10e firmware TowelRoot doesn't work. For root you can use this guide or PurpleDrake script for G3 - it works fine on LG L90.
Here is the link: http://goo.gl/0E3jMn
However, this guide still works!
#include /* * Your warranty is now likely void. * * I am not responsible for bricked devices, dead SD cards, * spontaneous combustion, or any other host of cosmic penalties * which may befall you, your family, or your phone. * */
The procedure is done for L90 but it also have to work on other similar 2014 year LG phones with kitkat as L40, L70, G2 mini and others (L80). Confirmed working!
Carrier branded phones are not supported as I can see from replies.
It is recommended to fully charge your phone before the procedure.
After the procedure the phone will be rooted and the hidden LG RCT utility will know about it. So your warranty is likely void.
So, let's go:
1.Format external sdcard using cardreader into ext2. I use Windows 7 so I installed MiniTool Partition Wizard from here to format my sdcard.
USE ONLY PRIMARY PARTITION, NOT LOGICAL! thnx for note to @wikid24
The reason to use ext2/3/4 partition is that ntfs/fat partitions are not detected by recovery.
You can also try ext4, if ext2 doesn't work for you!
3.Install LG drivers if you still didn't.
4.If you don’t have ADB on your computer: install Android SDK or just download ADB.rar and unpack it somewhere (e.g. C:/ADB/ )
5.Prepare your phone. Turn on USB debugging: Settings – General – Developer options – USB debugging.
If you don’t see it: Settings – General – About phone – Common – Software info – click 5-10 times on Build number.
Added by @Cliffwiggum about L40c/L70c versions:
I successfully rooted the LG optimus zone 2 from Verizon prepaid which is the LG L40c, as well as the LG optimus exceed 2 which is the LG L70c. In order to get either phone into USB debugging mode I had to connect my phone as Internet -> Ethernet (instead of MTP) before USB debugging mode would turn on.
ATTENTION! On the first connection to computer it will ask you to allow USB debugging.
7. Open ADB. (I use Shift+RightClick on ADB folder and choose Open command line)
8.In the opened window type the next line and press Enter.
List of devices attached LGD410a123456 device
adb shell reboot recovery
9. Now you can unplug your phone. Plug in your sdcard.
Navigation: Volume+/- = Up/Down; Power = Choose.
Then choose “reboot system now”
The phone will reboot.
You are ROOTED!
To unroot and save your warranty you just have to reflash the ROM by LG Mobile Support Utility - Upgrade recovery option.
LG RCT tool will forget that it was ever rooted. All the settings (except those that need root) will be kept.