Root LG K40 LM-X420 / Bootloader Unlock & TWRP

LG K40 can be rooted after unlocking the bootloader and flashing a custom recovery such as TWRP. Using the custom recovery we can install a flashable Magisk or SuperSU zip file to root the device.

I’m trying to root my LG K40 MetroPCS with model number LM-X420MM. There are different variants of K40 based on different carriers. The other K40 variants are T-Mobile lmx420tm, AT&T lmx420as, factory unlocked lmx420qn, US Cellular lmx420qm & Spectrum Mobile lmx420qn.

Let’s start the procedure by unlocking the bootloader.

LG K40 Bootloader Unlocking – LMX420MM

To unlock the LG K40 bootloader we need to do the following steps –

1. Turn on the “Developer Options”

“Developer Options” is hidden by default but can be enabled quite easily. Follow this post to enable it on your K40 – LG K40 Developer Options.

2. Enable USB Debugging

After doing the first step, Go to Developer Options and enable USB Debugging.

lg k30 root

3. Connect K40 to PC via USB Data Cable

Now we are ready to connect our phone to the PC via USB data cable.

lg k30 lge mobile adb interface driver

Wait for the LGE Mobile ADB interface driver to install, after connecting the phone.

4. Use Minimal ADB & Fastboot Tool for Bootloader Unlocking

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