Firmware General Mobile GM 21 Plus

OS: Android 11

CPU: Octa-core (4x2.3 GHz Cortex-A53 & 4x1.8 GHz Cortex-A53)

RAM: 3GB 32GB / 4GB 64GB

Display: 6.53 inches, 102.6 cm2 (~82.3% screen-to-body ratio)

Camera: Main: 16MP, (wide), F/2.0
Depth: 2MP
Depth: 0.3MP

Battery: Non-removable Li-Po 5050 mAh battery

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.
- Turn off your smartphone with the Power button.
- 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 buttons: Volume up (or Volume Down) (+Home) + Power together for a short time.
- Recovery mode will appear on the screen.
- Use the volume buttons to navigate the menu, and use the Power button to select.
- Next in the menu, select 'Wipe data / factory reset'.
- Select 'Yes - delete all user data' and confirm your choice with the Power button.
- Then select 'Wipe cashe partition' from the menu.
- Select 'Yes - Wipe cache' and confirm with the Power button.
- Use the volume buttons to select 'advanced'.
- Select 'Wipe Dalvik Cache' and confirm with the Power button.
- Then select 'Yes - Wipe Dalvik Cache' from the menu.
Go back, press 'Go Back'.
- Use the volume buttons to select 'mounts and storage' .
- Next in the menu, select 'format / system' .
- Then select 'Yes - Format' from the menu.
Go back, press 'Go Back'.
- Highlight 'install zip from sdcard' .
- Next in the menu, select 'choose zip from sdcard' .
- After that, select the item 'Yes - Install your firmware name' from the menu.
- Then select 'Reboot system now' from the Recovery mode 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. This is done by analogy with CWM.
- Perform a factory reset. When finished cleaning the phone, return to the original menu by pressing the 'Back' key.
- In the main menu, select 'Install' 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.
- Upon completion, the utility will automatically display a message about successful flashing. 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 firmware image to the folder with 'ADB'
- Next, you need to put your device into fastboot mode and write a request in the command line: fastbooflash zip filename.zip.
- Wait for the end of the installation and reboot the device.

Thomas Nilan
Smartphone Expert

Thomas Nilan is a mobile phone expert with in-depth knowledge of the Android and iOS operating systems, who understands the settings of various hidden features that allow you to expand the capabilities of your smartphone, as well as get information about what is going on inside the phone for future repairs. He is an authority in his field, which has allowed him to become a ghostwriter for several technology publications, and he enjoys writing small mobile applications for testing smartphones.