September 15, 2018

Flash Custom ROM (A-Z Guide)

The most boring thing about Android Update from device manufacturers is that the updates don't come consistently. In fact few devices receive OTA updates and most don't at all. As a result of which if your device does not have a strong developer community you will be stuck with the out of the box version of Android OS and cannot enjoy latest version out in the market.

Naturally the question that ponders in mind is how to Flash Custom ROM on Android Phone? Is it possible to Flash Custom ROM without PC? Or do we need to Flash Custom ROM on computer?

In this article, I have written about how can we easily flash Custom ROMs (without PC) on our android phones. Let's get started.

What is a ROM?

Even though ROM stands for Read only Memory, when it comes to android we straight forward refer to it as the entire core software entity. The OS, as few like to call it. Now we can relate this with different version is Linux distribution, if I assume you know about Linux.

So the device manufacturer's ROM at certain time turns out to be different from what we wanted or calling it out-dated . In that case, what comes into play is custom ROM. Imagine if you wanted to keep your expensive phone bought from your hard earned money but update the version of Android OS in it. Everytime new version of Android is released, you got to buy a new device. We must be thankful to Devs who work for us, keeping in mind about our needs and releasing Custom ROM for our device.

How to Flash Custom ROMs in an Android phone?
A-Z Guide to Flash Custom ROM

Prerequisites to install custom ROM on Android:

  1. ADB and Fastboot tools
  2. TWRP/CWM recovery file
  3. ROM zip file
  4. Gapps zip file
  5. PC (obviously)
  6. Data Cable/USB Cable
  7. Patience

How to flash custom ROM on Android? (step by step)

To flash custom ROM on your existing android device you need to have an unlocked bootloader and a custom recovery also. There are device specific methods of unlocking bootloader and most often you find them in YouTube. When it comes to a custom recovery the most widely spread name is TWRP (TeamWin Recovery Project) and CWM (ClockWorkMod). Both of them serve the same purpose but like mentioned before they come device specific.

Below I have mentioned steps to Flash a Custom ROM on Android Devices:

  1. First step involves the unlocking of bootloader using adb commands.
  2. After bootloader is unlocked then using adb commands yet again reboot your device to fastboot mode.
  3. When it is turned to Fastboot mode now you are to type fastboot recovery flashing command to flash new custom recovery to your device's recovery partition.
  4. With that being done, your device will now reboot into the newly flashed TWRP or say custom recovery.
  5. I believe you have already downloaded the custom ROM zip file as well as the GApps file from dedicated website and saved them in the external SD card.
  6. The next step involves restarting your device to TWRP recovery and taking a nandroid backup of this ROM. This is normally done to avoid any mess that comes out because of our half-knowledge.

  7. TWRP recovery

  8. While taking backup remember to select the partitions as you can see in the image below. Swipe as instructed. The backup will take an ample amount of time depending on how much data is saved in the existing ROM.

  9. How to Flash Custom ROMs in an Android phone?

    [NOTE: Remember to select storage that has abundant space left.]

    Select Storage

  10. Once the backup is complete its time to wipe the partitions in order to flash our custom ROM.

  11. How to Flash Custom ROMs in an Android phone?

  12. Goto Wipe and select Advanced Wipe. Next select Dalvik/ART Cache, System, Data, Cache partitions. See below.

  13. Wipe Partitions

  14. With all the wiping tasks done, we have to install the custom ROM. So now head over the Install.

  15. How to Flash Custom ROMs in an Android phone?

  16. Navigate to the directory where you have saved your files. If it is in the Micro SD card then you have to click on Select Storage button and then Choose the required storage. 
  17. Tap on the ROM zip file and then come back to select the Gapps file. Swipe once you've selected both of them.

  18. How to Flash Custom ROMs in an Android phone?

    How to Flash Custom ROMs in an Android phone?

  19. You're done. Now device wil reboot and this initial reboot takes about 4-5 mins. So don't panic. 

After this, if you want you can definitely root your new ROM by flashing Magisk Module.

Final Words

The entire process mentioned above is only for educational purposes and if any damage caused to your device, only you will be held accountable for that.

Truly, you must follow the steps properly and in case you have any questions, comment below. Make sure you subscribe to our newsletter to get interesting updates from TechGyd.