If you’re unfamiliar with the term, “to flash a ROM” to an Android smartphone simply means loading a different Android OS version on the phone. It could be a custom ROM, for example, which might have additional features, facilitate extended battery life and so on. Alternatively, it could be an AOSP or a CyanogenMod, which are basically stock Android versions stripped of any OEM or carrier elements, and possibly additional features.
The objective of flashing a new ROM is various. You might want some amazing new features not found on your Android version; you may just want a stock version with no bloatware, or you might want the latest Android before your manufacturer makes it available. No matter what the purpose, there’s usually a custom ROM for it.
Flash a new ROM to Android –
Flashing a new ROM is not a complex process, but it requires following a set of instructions. It also requires you to know exactly what you’re after, otherwise, you could find yourself repeatedly flashing ROMs to your smartphone in search of something better.
One misconception with flashing a new ROM is that you need to root your Android phone. That’s not necessary. All you need to do is unlock the bootloader and flash a custom recovery. However, since many custom ROMs require root access, the process might involve what you understand as rooting the device.
Step 0: The first thing to do is backup your device. Flashing a new ROM typically wipes all the data from your phone, so you want something with which you can recover that data.
Step 1: Download the ROM that you want. At this point, you need to be very careful to choose the right one. There might be multiple variants of your device based on which carrier you use, and so on. Be sure that the one you download is the correct one.
Step 2: Once you download the ZIP file to your SD card, do not extract it. Before doing anything you need to find the matching GApps that supports the same version as the ROM. Save that to your card as well.
Step 3: Now boot into recovery. On most devices, you hold down the power and vol down buttons together for 5 seconds. You should be able to see something like this if you’re using TWRP:
Step 4: Tap on “Install”, select and flash the ZIP. You will likely get an alert that you need to get past by confirming.
Step 5: Once the installation is done, go back and clear your cache.
And that’s about it. There are also several software applications to flash a new ROM to your Android phone, but this is one of the most common methods.
Things to do Before and After a Custom ROM Flash
There are several things you need to do in order to prepare for a ROM flash. Aside from doing the backup, you will need a custom recovery like Team Win Recovery Project (TWRP) or ClockworkMod. You also need to make sure your battery is near full since flashing takes time and could draw more power than normal usage. You will also need to have enough memory on your SD card since ROMs can easily go up to 1.5GB or more. You will also need to turn on Debugging Mode.
For Samsung users, you might need to backup your IMEI as well because flashing sometimes wipes the folder that stores this critical identification code. If that happens and you haven’t done a backup of your efs partition, you won’t receive a network signal. You will also need to backup your current ROM, and this is best done on an external storage device. If your phone gets stuck in a boot loop and you don’t have this externally, you might not know what to do.
After your new ROM is flashed to your phone, avoid recovering previously backed up data or apps on the new ROM. The reason is that backup apps are usually designed to recover data to the same ROM as the one they did the backup on. If you don’t follow this rule, discrepancies in the system files of the two ROMs might affect your device’s performance. That might be counterproductive to why you flashed a new ROM in the first place.