Firmware Asus Zenfone 4 A400CXG

OS: Android v4.3 (Jelly Bean), upgradable to v4.4 (KitKat)

CPU: Dual Core Processor

Display: 4 inches, 480 x 800 pixels

Camera: 5 MP

Battery: 1600 mAh

Before flashing, you need
Create a full backup of the firmware.
The battery must be 100% charged.

1. Flashing your phone using CWM Recovery
2. Flashing the phone using TWRP Recovery
3. Flashing the phone using Fastboot

1. Phone flashing using CWM Recovery
The rich functionality of CWM Recovery www.clockworkmod.com allows you to perform many manipulations with the device, including rolling the firmware. By default, stock Recovery is installed in the devices, which means that first you need to install the ClockWorkMod Recovery utility itself.
The general firmware process described below is for ZIP files. Instructions: - Download the firmware and place it on your phone's SD card.
- Next, turn off your phone.
- Clamp a certain sequence of buttons on the phone case. The set of keys may vary depending on the manufacturer of the device. A universal option is to set the following clicks.
- Press the Power + Volume up (or Volume Down) (+Home) buttons together for a few seconds.
- The phone will then boot into Recovery mode.
- Use the volume buttons to navigate the menu, and use the Power button to select.
- From the Recovery mode menu select 'Wipe data / factory reset'.
- Select 'Yes - delete all user data' from the menu and press the Power button.
- From the Recovery mode menu select 'Wipe cashe partition'.
- Select 'Yes - Wipe cache' from the menu and press the Power button.
- Use the volume buttons to select 'advanced'.
- Select 'Wipe Dalvik Cache' from the menu and press the Power button.
- From the menu select 'Yes - Wipe Dalvik Cache'.
Go back, press 'Go Back'.
- Use the volume buttons to select 'mounts and storage' .
- From the menu select 'format / system' .
- From the menu select 'Yes - Format' .
Go back, press 'Go Back'.
- Highlight 'install zip from sdcard' .
- From the menu choose 'choose zip from sdcard' .
- From the menu select 'Yes - Install your firmware name' .
- Select 'Reboot system now' from the menu.

2. Flashing the phone using TWRP Recovery
For those who prefer working with the utility in the form of TWRP Recovery, the following instructions for the step-by-step installation of the update in the form of a ZIP archive are offered:
- Upload the file with the firmware image to the SD card of your phone.
- Go to TWRP Recovery. In the same way as in CWM.
- Perform a factory reset. When the operation is completed return to the original menu by pressing the 'Back' key.
- From the main menu select 'Install' and find and select the firmware file. Click on it by dragging the slider to the side.
- After that, the firmware process will start. This will take about 2-3 minutes.
- When the firmware operation is completed, you must click on the 'Reboot System' item, and reboot the device.

3. Flashing the phone using Fastboot
A universal tool for flashing Android smartphones using a PC is the Fastboot utility. It is part of the SDK Platform Tools, which means it is suitable for a large number of devices.
Before starting the firmware, you need to get access to the system kernel. Very often, many manufacturers block this system parameter, not wanting users to change the system files of their firmware images with their own hands. To do this, you need to unblock Bootloader. To do this, you need to study the detailed instructions for configuring and managing the command line. Before starting the firmware using a computer, do not forget to enable USB debugging of the device in the engineering settings of the device.
- Copy the .zip archive with the image, and place it in the folder with 'ADB'
- Put your device into fastboot mode and write a prompt in the command line: fastbooflash zip filename.zip.
- Wait for the end of the installation and reboot the device.