How to Setup the Android Debug Bridge (ADB)

1. Launch the Settings application on your phone.
2. Tap the About Phone option generally near the bottom of the list (this is hidden behind the “System” option in Google’s latest Android Oreo version).
3. Then tap the Build Number option 7 times to enable Developer Mode. You will see a toast message when it is done.
4. Now go back to the main Settings screen and you should see a new Developer Options menu you can access.
5. Go in there and enable the USB Debugging mode option.
   
6. You are partially done with the phone setup process. Next up, you will need to scroll below and follow the rest of the instructions for your particular operating system.

Microsoft Windows ADB Setup

1. Download the ADB ZIP file for Windows
2. Extract the contents of this ZIP file into an easily accessible folder (such as C:\adb)
3. Open Windows explorer and browse to where you extracted the contents of this ZIP file
4. Then open up a Command Prompt from the same directory as this ADB binary. This can be done by holding Shift and Right-clicking within the folder then click the “open command prompt here” option. (Some Windows 10 users may see “PowerShell” instead of “command prompt”.)
5. Connect your smartphone or tablet to your computer with a USB cable. Change the USB mode to “file transfer (MTP)” mode. Some OEMs may or may not require this, but it’s best to just leave it in this mode for general compatibility.
6. In the Command Prompt window, enter the following command to launch the ADB daemon: adb devices
7. On your phone’s screen, you should see a prompt to allow or deny USB Debugging access. Naturally, you will want to grant USB Debugging access when prompted (and tap the always allow check box if you never want to see that prompt again).
8. Finally, re-enter the command from step #6. If everything was successful, you should now see your device’s serial number in the command prompt. Yay! You can now run any ADB command on your device! Now go forth and start modding your phone by following our extensive list of tutorials!

How to Install ADB on macOS

1. Download the ADB ZIP file for macOS
2. Extract the ZIP to an easily-accessible location (like the Desktop for example).
3. Open Terminal.
4. To browse to the folder you extracted ADB into, enter the following command: cd /path/to/extracted/folder/
5. For example, on my Mac it was this:cd /Users/Doug/Desktop/platform-tools/
6. Connect your device to your Mac with a compatible USB cable. Change the USB connection mode to “file transfer (MTP)” mode. This is not always required for every device, but it’s best to just leave it in this mode so you don’t run into any issues.
7. Once the Terminal is in the same folder your ADB tools are in, you can execute the following command to launch the ADB daemon: adb devices
8. On your device, you’ll see an “Allow USB debugging” prompt. Allow the connection.
9. Finally, re-enter the command from step #7. If everything was successful, you should now see your device’s serial number in macOS’s Terminal window. Congratulations! You can now run any ADB command on your device! Now go forth and start modding your phone by following our extensive list of tutorials!

How to Install ADB on Linux

1. Download the ADB ZIP file for Linux
2. Extract the ZIP to an easily-accessible location (like the Desktop for example).
3. Open a Terminal window.
4. Enter the following command: cd /path/to/extracted/folder/
5. This will change the directory to where you extracted the ADB files.
6. So for example:cd /Users/Doug/Desktop/platform-tools/
7. Connect your device to your Linux machine with your USB cable. Change the connection mode to “file transfer (MTP)” mode. This is not always necessary for every device, but it’s recommended so you don’t run into any issues.
8. Once the Terminal is in the same folder your ADB tools are in, you can execute the following command to launch the ADB daemon: adb devices
9. Back on your smartphone or tablet device, you’ll see a prompt asking you to allow USB debugging. Go ahead and grant it.
10. Finally, re-enter the command from step #8. If everything was successful, you should now see your device’s serial number in the Terminal window output. Congrats! You can now run any ADB command on your device! Now go forth and start modding your phone by following our extensive list of tutorials!

Some Linux users should be aware that there can be an easier way to install ADB on their computer. The guide above will certainly work for you, but those own a Debian or Fedora/SUSE-based distro of Linux can skip steps 1 and 2 of the guide above and use one of the following commands. . .

• Debian-based Linux users can type the following command to install ADB: sudo apt-get install adb
• Fedora/SUSE-based Linux users can type the following command to install ADB: sudo yum install android-tools

Just to cover all of our bases here, Linux users may need to put a ./ in front of the ADB commands we list in future tutorials. This is something that is likely known by any Linux user already, but again, we want as many people as possible to understand how to do these tweaks for Android no matter how much of your operating system you know.

Bonus: For those who want to take this a step further, you can follow this new tutorial we put together that will walk you through how to setup ADB so that you can use the command from any directory on a Windows or Linux desktop.

Download the ROM which we have listed in this table below. This guide is helpful to those who are looking to Downgrade or upgrade your smartphone. You can anytime flash the stock ROM on Gretel A7. This guide is also helpful to unbrick the phone (revert back from death), you can install the Stock Firmware build to revert back to old version also. Also if you feel your Gretel A7 lag or has any issue, then flash the stock firmware from the list below and save from situation. Stock Firmware doesn’t void a warranty on your Gretel A7.

Here are below of Android 6.0 Marshmallow firmware Update for Gretel A7. To install the Stock Firmware on Gretel A7, Please follow the guide and download the ROM and SP Flash Tool on your computer. This guide is for How to Install Stock ROM on Gretel A7 smartphone.

The Advantage Of Stock Firmware:

• Flash Stock To Unbrick your Gretel A7
• Flash Stock ROM to Fix the Bootloop problem
• Upgrade and Downgrade Gretel A7
• Unroot or Fix Bugs on your phone
• To fix the lag or stutter on Gretel A7
• By flashing Stock ROM, you can solve software problems.
• Revert back to stock to gain your warranty.

READ THIS CAUTION:

So before jump into the manual upgradation setup, please make sure you have a good amount juice with at least 80% Charge. If not please charge the phone. Backup your phone in case if you need it later. If you brick the device we are not responsible. Do it at your own risk. Remember this guide is to update Stock ROM on Gretel A7.

How to Install ADB on macOS

1. Download the ADB ZIP file for macOS
2. Extract the ZIP to an easily-accessible location (like the Desktop for example).
3. Open Terminal.
4. To browse to the folder you extracted ADB into, enter the following command: cd /path/to/extracted/folder/
5. For example, on my Mac it was this:cd /Users/Doug/Desktop/platform-tools/
6. Connect your device to your Mac with a compatible USB cable. Change the USB connection mode to “file transfer (MTP)” mode. This is not always required for every device, but it’s best to just leave it in this mode so you don’t run into any issues.
7. Once the Terminal is in the same folder your ADB tools are in, you can execute the following command to launch the ADB daemon: adb devices
8. On your device, you’ll see an “Allow USB debugging” prompt. Allow the connection.
9. Finally, re-enter the command from step #7. If everything was successful, you should now see your device’s serial number in macOS’s Terminal window. Congratulations! You can now run any ADB command on your device! Now go forth and start modding your phone by following our extensive list of tutorials!

Unlock Bootloader

Enable developer option and usb debugging.Guide  How to Enable Developer Options, USB Debugging and OEM Unlock on Android

Unlock Bootloader Of Any Android Using Fastboot Commands

• Connect your android to your PC with USB cable
• Now go to ADB & fastboot folder and Open the command window there(Right click on the empty space inside the folder then select “Open command window here” or “Open PowerShell Window Here” option to launch a command window
• Now reboot into the bootloader by issuing the following commands. (Make sure your device is detected by your PC)

$ adb reboot bootloader

• Now Check fastboot connectivity by giving the command below.If your device is connected properly then it should return device code.

$ fastboot devices

• Once in the bootloader, issue the following fastboot command to unlock the bootloader. (This will unlock your phone and wipe all data of your device)

$ fastboot oem unlock

• Done!!! Reboot the phone and boot into your unlocked device. Use command:

$ fastboot reboot

If you use Mac or Linux machine, use the code: “./fastboot oem unlock” for iOS and “sudo fastboot oem unlock” on Linux.

Installing Custom Recovery

Download Files

TWRP Recovery (3.0.2)

TWRP Recovery (3.1.1)

Download TWRP Recovery (3.2.1-0)

Khởi động vào bootloader

$ adb reboot bootloader

Khi vào chế độ fast mode

trên terminal gõ lệnh

$ fastboot flash recovery “path file twrp-3.2.1-0-Gretel_A7.img”

Đã xong transfer thì gõ tiếp lệnh

$ fastboot reboot

SuperSU

Temporarily Booting TWRP

Download SuperSU-v2.46 to your device.

Boot into TWRP temporarily, if you have flashed the TWRP skip this step. Restart and then boot into TWRP

adb reboot bootloader

fastboot boot (pull the twrp.img into cmd)

Eg.

fastboot boot D:\Kingo ROOT\tools\twrp-3.0.2-0-flounder.img

fastboot reboot

Tap on “Install” and select the SuperSU zip file that you downloaded to your device. “Swipe to Confirm Flash” at the bottom of screen to begin the flash. This will install SuperSU and allow root access automatically.

Reboot device.

If you want to verify root access, download and install Root Checker.apk from the Play Store.

FINAL

STEP INSTALL ROM TO DEVICES

• List ROM for Gretel A7

$ adb reboot bootloader

Khi điện thoại đã vào fastboot mode thì chạy tiếp lệnh

$ fastboot boot “path file twrp.img tương ứng với device”

ví dụ :

$ fastboot boot twrp-3.2.1-0-Gretel_A7.img

twrp-3.2.1-0-Gretel_A7.img là một trình cài đặt ROM, Gapps

(xda)

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