HOW TO FLASH A FIRMWARE IN ANDROID BY ODIN

WHAT IS FIRMWARE 

Firmware is a software program or set of instructions programmed on a hardware device. It provides the necessary instructions for how the device communicates with the other computer hardware. But how can software be programmed onto hardware? Good question. Firmware is typically stored in the flash ROM of a hardware device. While ROM is "read-only memory," flash ROM can be erased and rewritten because it is actually a type of FLASH MEMORY.

Firmware can be thought of as "semi-permanent" since it remains the same unless it is updated by a firmware updater. You may need to update the firmware of certain devices, such as HARD DRIVES and video cards in order for them to work with a new OPERATING SYSTEM. CD and DVD drive manufacturers often make firmware updates available that allow the drives to read faster media. Sometimes manufacturers release firmware updates that simply make their devices work more efficiently.

You can usually find firmware updates by going to the "Support" or "Downloads" area of a manufacturer's website. Keeping your firmware up-to-date is often not necessary, but it is still a good idea. Just make sure that once you start a firmware updater, you let the update finish, because most devices will not function if their firmware is not recognized.

STEPS TO FLASH A FIRMWARE IN ANDROID

Step One: 

Unlock Your Boot loader and Flash a Custom Recovery

First, let's clear up some confusion: Contrary to popular belief, you do not actually need to root your phone to flash a ROM—you just need to unlock your bootloader and flash a custom recovery. However, this process usually goes hand-in-hand with rooting—and most custom ROMs come with root access—so what you think of as "rooting your phone" is probably what you're going to have to do first.

Unfortunately, we can't go through this step in detail here, because it's different for every phone! So, hat all the different terms mean, and what to watch out for. Then, search around sites like XDA Developers for instructions on how to unlock the bootloader of your specific phone, which recovery you should use (usually TWRP or ClockworkMod), and how to flash it.

I also recommend rooting your phone during step one, since it'll make the backup process in step two easier—and save you some hassle along the way. A lot of methods and one-click apps will root your phone anyways, so it might be included in the process. Again, this can vary from phone to phone. (If the instructions require you to flash SuperSU.zip, you can refer to step three of this guide for info on how to do that—ironically, it's just like flashing a ROM).

NOTE:  Unlocking your bootloader will most likely wipe your phone, and without root access, you won't be able to back up very much. So, save anything you want to keep on your computer—you will have to set up your phone from scratch just this once before continuing.

Step Two: 

Make a Backup of Your System, Apps, and Data

Now that you've got a custom recovery on your phone, the first thing you should do—before you ever make a big change to your system—is back it up. First, we'll make a Nandroid backup, which is basically a image of your current system. That way, if something goes wrong, you can restore your phone to exactly the way it was before you started tweaking. This will save you a lot of hassle if something goes wonky (which, let's be honest, can happen often). To do this:

1. Reboot your phone and enter recovery mode. This is a bit different on every phone, but usually involves some permutation of pressing the power and volume buttons at the same time.
2. 
   
3. Head to the "Backup" or "android" section of your recovery mode. The default settings should be fine. If given the option, give your backup a name that helps you remember what it is (like "Pre-CyanogenMod Backup 01-17-14"). Confirm your backup and let it run.
4. 
   
5. Wait for the backup to finish. This may take awhile.
6. 
   

Use Odin to Flash Samsung Galaxy Stock Firmware

1.  DOWNLOAD ODIN

2. If you own a Samsung phone and enjoy rooting or modding your device, flashing official firmware can be very useful. Odin is Samsung's own internal program for loading such updates for testing purposes, and it's quite easy to use for your own custom modification needs.
   Though Odin is fairly simple, there are a few requirements and basics you'll need to learn first. While you can use some hacking to get Odin on a Mac, the native program works only with Windows. We will focus on instructions for use on a PC in this article.

Requirements

• Windows PC

• USB data cable

STEP ONE:      Find Odin Firmware Files

If you're looking for the actual firmware you need to flash, it can sometimes be difficult to locate online. For any older Samsung device, the best place to look is typically in the corresponding  XDA forum. Many users post stock and beta firmware in these forums. If you are lucky enough to have a recent Samsung flagship, you can download the desired firmware from the Samsung Firmware Science website.

STEP TWO:    Extract the Firmware Files

right-click on the Odin firmware ZIP file and choose "Extract all." Inside the extracted archive, you will see five MD5 files (pictured below)

STEP THREE:  Install the Right Drivers

Your PC needs the necessary drivers to interface with your Samsung phone. Samsung maintains an official web page where you can grab the drivers you need. Download the drivers and run the setup to install them on your PC, then reboot your computer to make sure they've been applied. Don't skip this step, as it could cause issues with operating the Odin executable file.

STEP FOUR:  Install Odin on Your PC

The Odin software only works with Windows, so make sure to have a PC handy. First, download the latest version of Odin. Extract the ZIP file for the latest version and run the EXE file inside of it to launch Odin.

STEP FIVE:     Put Your Phone in Download Mode &                                                     Connect to PC

With the device turned off, press Power + Volume Down + Home to enter Download Mode. Some older devices use a different button combination. To find the exact key combination for your device, just do a simple Google search — for instance "Galaxy S3 download mode." At this point you can connect the phone to your PC using the USB data cable.

Newer Galaxy phones without a home button will require a different button combo to enter Download Mode (Volume Down + Bixby + Power)

STEP SIX:   Flash the Firmware Files

Head back to the Odin application. Click on the 'BL' button, then choose the file that starts with "BL" inside your extracted firmware folder. Next, click on the 'AP' button in Odin and choose the AP file inside your extracted firmware folder. Click on the 'CP' button, choose the CP file inside your extracted firmware folder. Click on the 'CSC' button, choose the HOME_CSC file inside your extracted firmware folder.

Make sure you choose the HOME_CSC, and not CSC file. The USERDATA button is not necessary or needed for this process. Verify that all four files are loaded and that check marks appear next to each button. Click on the "Start" button at the bottom of the Odin application when you're ready.

The flashing process will begin and should take about 10–12 minutes. It may take some time for your device to reboot, but don't be alarmed. When your device finally boots up, you should now be running your desired firmware. If you want to check that the correct firmware is installed, head to Settings –> About Phone –> Software Information. The firmware number is located under "Baseband version."

Keep in mind that if you update to a beta or testing build, you may not be able to go back to the old firmware. If the bootloader is advanced on the new build, Odin may not work to downgrade to your previous software. Even in the likely case that you can downgrade to your old firmware, you will always need Odin to go back to a older build. Do not attempt sideloading methods to revert back.

Step 1