Guide to Flashing Stock ROM on Nothing Phone (2) via Fastboot

Spike

REQUIREMENTS:

Unlocked bootloader ( follow this guide )

Stock OTA Images for Phone (2) : nothing_archive
Fastboot Flashing Script For Phone (2)
15 Seconds Online ADB-Installer and Updater

DISCLAIMER:

This process involves data loss as clean flashing is done! Backup accordingly before proceeding.
It is assumed that you maintain functionality of your brain.exe and eyes.exe while following this guide.
We are not liable for any actions resulting from negligence or ignorance of the steps outlined in this guide.
Ensure your bootloader is unlocked and that USB and ADB fastboot drivers are correctly installed
Unlocking critical partitions is not necessary for this method!
Before continuing, reboot your device into bootloader mode.
Open the Device Manager and verify if "Android Bootloader Interface" appears.
Additionally, type the command "fastboot devices" in the command prompt and confirm if it returns the device ID.
You can downgrade your NOS version by the same method.

GETTING READY:

Fetch the stock OTA images and fastboot flashing script for the corresponding release of NOS version as per your device model from the above links.
You need to download "-image-boot.7z", "-image-firmware.7z and "-image-logical.7z-001-003" (all 3 parts)
Extract all folders together using 7zip by selecting all 5 at once. ( Choose 7zip from drop down menu > Extract to *\* ) | ( Linux users can unzip with this cmd: 7za -y x "*7z*" )
You will get 3 folders. Move all image files (.img) from all these folders after extraction to one root / new folder created. We will designate this as the "MAIN folder" in this guide.
Move the flashing script for the respective device corresponding to windows or linux in the main folder
You should now be having a total of 36 ".img" files + 1 ".bat / .sh" (flashing script)

METHODS OF FLASHING:

Users can choose either to clean or dirty flash as follows:

A. CLEAN FLASHING:

There is no rollback lock on NOS. So you can clean flash an older version of the stock rom as well (downgrade)

- Assuming that everything is followed properly, turn on internet and proceed with executing the script (.bat) file from MAIN folder. Choose the following on screen options for clean flashing:

Wipe data? ---> "Y"
Flash to both slots? ----> "Y"
Do you want to disable verfied boot? ---> "N" (if you want to relock bootloader later) | [ Note: For NothingMuch ROM by arter97 you need to select (Y) in this case which will be followed by a compulsory data format )
Flash logical partitions ---> Y
Reboot? ---> HOLD ON! Have you checked whether all partitions have been flashed properly without errors? If everything went as expected type "Y" to reboot the device automatically and congrats you are done! If NOT do not type anything and close the script. Your device should be in fastbootd mode probably. Reboot to bootloader mode by using vol and power keys and run the script again. If you reboot the device without all the partitions being flashed properly it can lead to (soft/hard) bricks or crashdumps.
If you have followed the steps properly your device should be booted into Nothing OS setup. Congrats your efforts paid off and your stock rom has been successfully flashed 👍
If you are still having doubts refer to this visual guide (by Techticks) alongside the steps written above. Its stated wrt Ph (2) but Ph (1) users can follow it as well as the basic flashing template remains the same!

B. DIRTY FLASHING: (Updating while retaining data)

It is recommended to backup data prior to flashing just in case you mess up in some way just to be sure!

The method for updating NOS version via fastboot flashing is similar to clean flashing with 2 different steps
Move the new OS version OTA images and flashing script accordingly in the MAIN folder
Run the script and choose ~ Wipe data : (N); Flash to both slots: (Y); Disable verified boot? : (N); Flash logical partitions : (Y) And if everything went fine, Reboot : (Y)
You should be updated to the new version without data loss!

TELEGRAM LINKS:

CREDITS:

arter97 & spike0en for Stock OTA Images Archive for Nothing Phone (2)
Hellboy017 and rest involved for maintaining the fastboot flashing script
Snoop05, Tigerking, Reindex & LukeSkyD for 15 Seconds Online ADB-Installer and Updater