This will format all your application data, format your system. Step 5: Choose CSE Flash option as we are downgrading the firmware.Click the folder icon to browse your computer and select the H34510d_00.kdz file. Select Type: CDMA ( Do not worry about selecting this option as Flashtool is modified only for devices with SIM, you can also choose the option 3GQCPT).
Make sure you have the latest LG drivers installed on your PC.
If you have any problems installing or running the Flash Tool then install the libraries on your Windows PC. Visual C++ Runtime Library is required in order to run LG Flash Tool 2014.This tool is required in order to flash the KDZ file onto your device. Install the LG Flash Tool 2014(extract files if compressed) on your PC.Download LG Firmware version H34510d from the download section for your T-Mobile LG Leon.This tutorial will guide you through the procedure and help you successfully get root access on your T-Mobile LG Leon LTE 5.1.1 Lollipop firmware. To downgrade the firmware, you need to go through the usual KDZ installation process for LG devices. So if you have updated your phone’s software, then any of the rooting methods won’t work at this moment including the 1-click root scripts, root APKs and others. Although we are downgrading to the previous firmware, it is still based on the Lollipop 5.1.1 Android version. However, if you are looking for root access on the latest firmware, then it is possible only by downgrading to the firmware version H34510d and then root it usually with a rooting application like Kingroot.
T-Mobile has pushed quiet a few updates to its firmware lately, taking it to version H34510e.
This device has been launched a few months ago and its T-Mobile variant has received the latest Android 5.1.1 Lollipop firmware. The best part about LG Leon is that it comes with Android Lollipop firmware out of the box. LG Leon is a mid-range phone with some fine specifications.