Flashing Guide - Nothing Phone 3a (asteroids)

Prerequisites

Warning: Your warranty is void. Unlocking the bootloader and flashing custom software is done entirely at your own risk.

Before you begin:

• Your bootloader must be unlocked.
• Make a full data backup — a clean flash will wipe everything.
• Ensure your device has at least 30% battery.
• Only flash files meant for Nothing Phone 3a/pro (asteroids).
• First boot may take 5–10 minutes. Do not interrupt or force reboot unless it exceeds 10 minutes.

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Unlocking the Bootloader

Unlocking the bootloader wipes all data on the device.

1. Enable Developer Options: go to Settings → About Phone and tap Build Number 7 times.
2. In Developer Options, enable OEM Unlocking and USB Debugging.
3. Reboot to fastboot mode:

   adb reboot bootloader
   

   Or hold Power + Volume Down while the device is off.

4. Verify the device is detected:

   fastboot devices
   

5. Unlock the bootloader:

   fastboot flashing unlock
   

6. Confirm the unlock on-device using the volume keys and power button.
7. The device wipes and reboots. Complete the initial setup, then re-enable Developer Options and USB Debugging.

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Installing a Custom Recovery

1. Boot into fastboot mode.
2. Temporarily boot into the custom recovery image to verify it works:

   fastboot boot recovery.img
   

3. Once booted into recovery, flash it permanently from within recovery (Advanced → Flash Recovery), or flash directly:

   fastboot flash recovery recovery.img
   

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Clean Installation

1. Boot into your recovery.
2. Go to Format Data → Confirm.
3. Apply Update and Sideload the ROM zip.
4. Reboot back into Recovery (optional for Gapps).
5. Reboot to System.

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Update (Dirty Flash)

Method 1: OTA Update

1. Go to Settings → System → System updates.
2. Download the latest available build.
3. Tap Reboot once the download finishes.
4. The device reboots into recovery and installs the update automatically.
5. Reboot to System.

Method 2: Recovery Flash

1. Reboot to Recovery.
2. Select Apply Update → Sideload Zip file.
3. Reboot to System.

Note: For vanilla builds, GApps must be reflashed after every update.

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Device Info

Field	Details
Codename	asteroids
SoC	Qualcomm Snapdragon 7s Gen 3
Android	15 (launch)
RAM	8 GB / 12 GB
Storage	128 GB / 256 GB (UFS 2.2)