How to reflash Android: a complete guide from preparation to installation

Flashing a smartphone to Android is a process that can either bring an outdated device back to life or turn it into a “brick” if done incorrectly. In 2026, when manufacturers are actively closing support for even flagship 2020-2022 models, the ability to independently update firmware becomes a critical skill. But how to do this safely, without losing data or disrupting the operation of camera modules or network chips?

This article is not just instructions, but a practical guide taking into account current trends: from unlocking the bootloader on new chips Qualcomm Snapdragon 8 Gen 3 to bypassing restrictions Google on installing unofficial firmware. We will analyze all the stages: from preparing a backup to choosing between stock ROM (official firmware), GSI (Generic System Image) and custom builds like LineageOS or Pixel Experience. We will pay special attention to the “pitfalls” that even experienced users are silent about - for example, why after updating the firmware it may disappear 5G or stop working NFC.

1. Why reflash Android: real reasons and myths

Many people believe that flashing is only needed to “overclock” a smartphone or install the latest version Android. In fact, there are many more reasons - and not all of them are obvious:

• 🔄 Restoring performance after a failure (for example, if the device is stuck on the logo or constantly reboots).
• 📱 Extension of support for models that the manufacturer abandoned (for example, Samsung Galaxy S20 officially not will receive Android 15, but custom firmware will fix this).
• 🛡️ Removing bloodware —pre-installed applications that cannot be disabled (especially relevant for Xiaomi, Realme i Oppo).
• 🔒 Increasing security: some custom firmwares (for example GrapheneOS) offer better protection against surveillance than stock Android.
• 🎮 Optimization for games: firmwares like DerpFest or ArrowOS can improve performance in Genshin Impact or Call of Duty Mobile.

However, there are also mythsthat are worth dispelling:

• ❌ “Reflashing always speeds up smartphone" - incorrect. On weak devices (for example, Redmi 9A), heavy custom firmware can, on the contrary, slow down operation.
• ❌ “After the firmware, the warranty expires” - partially true, but some manufacturers (for example, Google for Pixel) allow you to return the stock firmware before contacting the service.
• ❌ “Custom firmware breaks the camera” - depends on the model. On Samsung Exynos this is a common problem, but on Qualcomm cameras usually work fine.

⚠️ Attention: Firmware based on Android 14+ may require mandatory certification Google for the operation of services (for example, Google Pay or Netflix in HD). Check this before installation!

2. Preparing for flashing: backup, drivers and tools

First step - save all data. Even if you plan to flash the device without resetting (dirty flash), the risk of losing information remains. Here's what you need to do:

• 📱 Backup applications and data: use Swift Backup (requires root) or Titanium Backup (outdated, but works on older versions of Android).
• 📂 Copy of internal memory: connect your smartphone to the PC and copy the folders DCIM, Downloads, WhatsApp (if any).
• 🔑 Saving IMEI and serial numbers: write them down or take a photo (located in Settings → About phone or under the battery).
• 📋 Export settings: if you use Nova Launcher, Tasker or other customized applications, save their configurations.

Next - Installing the necessary software on a PC:

Don't forget check driver version for your device. On Windows, this can be done through Device Manager (section Portable devices or Other devices). For Mac/Linux standard drivers are usually sufficient, but you may need to install libusb.

⚠️ Attention: If you are using a laptop, make sure it is connected to the network. Interrupting the firmware process due to a low PC battery can lead to hard brick (irreparable damage).

3. Unlocking the bootloader: step-by-step guide

Without an unlocked bootloader (bootloader), it is impossible to install custom firmware. The process differs depending on the manufacturer:

• 📱 Google Pixel: unlocking is officially supported through the command fastboot flashing unlock.
• 📱 Xiaomi/Redmi/Poco: account linking is required Mi and waiting 7–168 hours (depending on the model).
• 📱 Samsung: unlocking is only possible on models with Exynos-processors (for Snapdragon options in the USA - not possible).
• 📱 OnePlus: unlocking is available, but may reset data (even if you selected fastboot flashing unlock_critical).

General algorithm for most devices:

1. Enable Developer mode (click on Build number 7 times in Settings → About phone).
2. Activate USB debugging and OEM unlocking in the developer menu.
3. Connect the device to the PC and do:

   adb reboot bootloader

4. Check the status of the bootloader:

   fastboot oem device-info

   (look for the line Device unlocked: false).

5. Unlock:

   fastboot flashing unlock

   (on some devices - fastboot oem unlock).

On devices with a chip MediaTek (for example Realme 9 Pro) unlocking the bootloader can lead to loss of IMEI. You can restore it only through the engineering menu or specialized utilities like MTK Meta Utility.

Make a backup of all data|

Charge the phone at least 70%|

Install drivers and Platform Tools|

Enable USB debugging and OEM unlocking|

Prepare a USB cable (better original)-->

4. Select firmware: stock ROM vs custom builds

The type of firmware determines what functions will be available, how stable the device will work and whether you will receive updates in the future. Let's consider the main options:

Official firmware (Stock ROM)

Suitable for:

• ✅ Restoring the device after failure.
• ✅ Refund of the warranty (if it is still valid).
• ✅ Obtaining maximum stability (especially on Samsung or Google Pixel).

Where to download:

• 🔗 Samsung: Frija, SamMobile, Sammobile Firmware.
• 🔗 Xiaomi: Xiaomi Firmware Updater or Mi Flash Tool.
• 🔗 Google Pixel: official website Google (section Factory Images).

Custom firmware

Popular options in 2026:

• 📱 LineageOS —the most stable and closest to stock Android.
• 📱 Pixel Experience —firmware with proprietary features Google Pixel (for example, Now Playing or Call Screen).
• 📱 ArrowOS —a balance between performance and customization.
• 📱 DerpFest —optimized for games and multimedia.
• 📱 GrapheneOS — for security paranoids (without services Google).

Where to look:

• 🔗 XDA Developers — forum with discussions and links to firmware.
• 🔗 Telegram channels developers (for example, @LineageOSupdates).
• 🔗 Official firmware sites (for example, lineageos.org).

⚠️ Attention: Firmware based Android 14+ may require mandatory certification Google for banking applications (for example, SberBank Online or TinkoffCheck this before installation!

5. Installing firmware via TWRP or Fastboot

There are two main ways to flash Android: via custom recovery (TWRP) or directly via Fastboot. The choice depends on the type of firmware and device.

Method 1: Installation via TWRP

Suitable for custom firmware (LineageOS, Pixel Experience etc.).

1. Download the firmware (usually in the format .zip) and place it in the internal memory or SD card.
2. Boot into TWRP:

   adb reboot recovery

3. Do wipe (cleaning):
   • For clean installation: Wipe → Advanced Wipe (select Dalvik, Cache, System, Data).
   • For update (dirty flash): enough Cache and Dalvik.

Method 2: Installation via Fastboot

Used for official firmware (for example, for Google Pixel or Xiaomi).

1. Unpack the downloaded firmware (usually an archive with files .img).
2. Connect the device in mode fastboot:

   adb reboot bootloader

3. Run the firmware script:
   • For Google Pixel: flash-all.bat (Windows) or ./flash-all.sh (Mac/Linux).
   • For Xiaomi: use Mi Flash Tool (select Clean all and lock to completely clear).

fastboot reboot

Important nuance: On some devices (for example, OnePlus 11after flashing through Fastboot it may be necessary unlocking the bootloader againThis is normal - just repeat the command. fastboot flashing unlock.

6. Solving problems after flashing

Even if you did everything correctly, problems may arise after flashing. Here are the most common ones and how to fix them:

If after flashing the device not detected by PC, try:

• 🔌 Reconnect the cable (it is better to use the original one).
• 🔄 Reinstall the drivers (for example, Samsung USB Driver or Qualcomm QDLoader).
• 📱 Reboot the device in fastboot manually (hold Volume down + Power).

Critical error: If after flashing the device does not respond to any buttons (the so-called hard brick), you may need EDL mode (Emergency Download Mode). For this you need a special cable or box (for example, Qualcomm 9008). It is almost impossible to do this at home - contact the service.

7. Optimization after flashing: settings, root and Magisk

Successful flashing is only half the battle. To make the device work quickly and stably, follow a few additional steps:

1. Initial setup

• 🔧 Disable unnecessary services Google v Settings → Google → Google Services (saves battery).
• 🔋 Activate Adaptive battery and limit background activity for unnecessary applications.
• 📶 If there are problems with the network, manually select the operator in Settings → Mobile network.

2. Obtaining root access (optional)

If you need root access (for example, for AdAway or Greenify), install Magisk:

1. Download the latest Magisk (.zip) from GitHub.
2. Reboot into TWRP and flash Magisk.zip.
3. Reboot and check root through the app Magisk.

Attention: On Android 14+ Magisk may not pass SafetyNet even with the module Universal SafetyNet Fix. In this case, try Magisk Delta or roll back to Android 13.

3. Performance optimization

For additional speedup:

• 🔄 Install a kernel with support EAS (Energy Aware Scheduling) - for example, Kirin or FrancoKernel.
• 🎮 For games, disable MIUI Optimization (on Xiaomi) or activate Force GPU Rendering in the developer settings.
• 🗑️ Clear the cache once every 1-2 months. TWRP once every 1–2 months.

8. Common mistakes and how to avoid them

Even experienced users sometimes make mistakes that lead to brick (turning the phone into a “brick”). Here are the most dangerous of them:

• 🚫 Incompatible firmware version (for example, firmware Redmi Note 10 Pro on Redmi Note 10). Always check the model in Settings → About phone → Model.
• 🚫 Using unofficial versions of TWRP. Download recovery only from the official website twrp.me or verified sources on XDA.
• 🚫 Interrupting the firmware process. Even if the device seems to be frozen, wait 10-15 minutes before forcing a reboot.
• 🚫 Installing GApps over existing. This leads to conflicts and endless reboots. Always do clean flash (full cleaning).
• 🚫 Ignoring instructions for wipe. For example, for LineageOS it is not enough to clear only Cache —you need to format Data.

The most dangerous error: firmware boot.img or dtbo.img from another model. This is almost guaranteed to lead to hard brick, and the device can only be restored through EDL or Qualcomm Firehose.

⚠️ Attention: On devices with Dynamic Partition (all smartphones running Android 10+), you cannot manually resize sections via TWRP. This will lead to data loss and possible brick.

FAQ: Answers to popular questions