Xiaomi 12S Ultra (thor) HyperOS 1 Android 14 Fastboot ROM + HyperOS 2 (Android 15) xiaomi.eu + TWRP Download

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Daniel

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The files you listed belong to the Xiaomi 12S Ultra with codename thor, including an official China HyperOS 1 Android 14 Fastboot ROM, a xiaomi.eu HyperOS 2 Android 15 custom ROM, and an unofficial TWRP recovery image. Xiaomi 12S Ultra users often complain about aggressive thermal throttling in long camera or gaming sessions, noticeable shutter lag and processing times for night photos, and inconsistent battery life after some updates, issues that some advanced users try to mitigate by moving to newer HyperOS builds, clean-flashing stock ROMs, or using custom ROMs with different tuning.

Critical Warning for Xiaomi 12S Ultra (thor)​


  • Only flash firmware built for codename thor (Xiaomi 12S Ultra); using ROMs for other Xiaomi models or codenames can permanently brick your phone.
  • The OS1.0.16.0.ULACNXM package is a China HyperOS build with no Google apps; the xiaomi.eu ROM is a custom multi-language build based on a China HyperOS 2 base—do not treat xiaomi.eu as official stock firmware.
  • Flashing Fastboot ROMs, custom ROMs, or TWRP requires an unlocked bootloader and can erase all user data; always back up internal storage before doing anything.
  • Anti-rollback and security checks may block downgrades between major Android/HyperOS versions; never attempt to flash older builds blindly when you are already on a newer branch.
Click to expand...

Xiaomi 12S Ultra Firmware Details​


DeviceXiaomi 12S Ultra (China)
Codenamethor
Typical model number2203121C (listed by firmware databases for Xiaomi 12S Ultra China)
ChipsetQualcomm Snapdragon 8+ Gen 1
Main OS familiesMIUI 13 / MIUI 14, HyperOS 1.0 (Android 14), HyperOS 2.0 (Android 15, base for xiaomi.eu build)
Featured official buildOS1.0.16.0.ULACNXM – HyperOS 1.0, Android 14, China Stable, Fastboot.
Featured xiaomi.eu buildOS2.0.212.0.VLACNXM – HyperOS 2.0, Android 15 base, repacked as xiaomi.eu_THOR_OS2.0.212.0.VLACNXM_15.zip.
Android versions (these files)Android 14.0 for OS1.0.16.0.ULACNXM; Android 15.0 for xiaomi.eu_OS2.0.212.0.VLACNXM.
File typesOfficial Fastboot ROM (.tgz images), xiaomi.eu custom ROM (.zip), and unofficial TWRP recovery image (.img).
Flashing toolsXiaomi Mi Flash Tool / Fastboot for
Code: 
thor_images_*.tgz
; Fastboot + custom recovery (TWRP) for xiaomi.eu ROM.
Changelog (OS1.0.16.0.ULACNXM)Xiaomi ROM index shows: “Updated the security patch to December 2024. Increased system security.”
Common user complaintsReports of heating and throttling during intensive camera or gaming use, big image processing delays in some shooting modes, and uneven battery drain after certain updates.

Download Firmware for Xiaomi 12S Ultra (thor)​


Below are the exact ROMs and recovery image from your table, cross-checked against firmware trackers and download indexes for the Xiaomi 12S Ultra (thor). Choose the official HyperOS 1 Fastboot ROM if you want a stable stock base, or the xiaomi.eu ROM if you need a multi-language, Google-ready custom build; TWRP is primarily for advanced flashing and backup tasks.

  • Filename: thor_images_OS1.0.16.0.ULACNXM_20241224.0000.00_14.0_cn_481a059036.tgz
  • Size: 6.97GB (your link) / around 7.1 GB reported for OS1.0.16.0.ULACNXM Fastboot on ROM index sites.
  • Build Date: 2024-12-24 (from filename; tracker lists December 2024 HyperOS 1 update).
  • Build Version: OS1.0.16.0.ULACNXM (China, Stable, HyperOS 1.0)
  • Android Version: 14.0
  • Changelog: Updated the Android security patch to December 2024 and improved overall system security for Xiaomi 12S Ultra.
  • Notes: Recommended for users staying on official China HyperOS 1; ideal for full stock restore, fixing heavy software issues, or re-basing before trying custom ROMs.
  • Download Link: Xiaomi BigOTA (China Fastboot)



  • Filename: xiaomi.eu_THOR_OS2.0.212.0.VLACNXM_15.zip
  • Size: ~5.57GB from your table; SourceForge shows about 6.0 GB for this file.
  • Build Base: OS2.0.212.0.VLACNXM – HyperOS 2 China, Android 15.
  • Android Version: 15.0
  • Type: Custom multi-language ROM (xiaomi.eu) based on China HyperOS 2; includes Google services and removes many China-only apps.
  • Notes: Not an official Xiaomi ROM; intended for advanced users with an unlocked bootloader, typically flashed via TWRP or fastboot scripts included by the xiaomi.eu team.
  • Download Link: SourceForge (xiaomi.eu mirror)



  • Filename: twrp-3.7.1_12-v9.0_A15-thor-skkk.img
  • Size: 100MB (your table)
  • Type: Unofficial TWRP recovery image for thor (Xiaomi 12S Ultra), tuned for Android 15 kernels and partitions.
  • Notes: Used to flash custom ROMs (including xiaomi.eu), make full backups, and manage advanced operations; misuse can cause bootloops or decryption issues, so it is only recommended if you understand custom recovery workflows.
  • Download Link: SourceForge (TWRP image)


The Requirements​


  • Xiaomi 12S Ultra device with codename thor, confirmed via Fastboot (
    Code: 
    fastboot getvar product
    →
    Code: 
    thor
    ).
  • Unlocked bootloader using Xiaomi’s official unlock procedure.
  • Windows PC with Xiaomi USB drivers and the latest Android platform-tools (ADB/Fastboot).
  • Reliable USB-C cable and a stable connection; avoid any disconnection during flashing.
  • Xiaomi Mi Flash Tool for the
    Code: 
    thor_images_OS1.0.16.0.ULACNXM
    Fastboot firmware; TWRP and xiaomi.eu ROM require Fastboot and/or custom recovery usage.
  • Complete backup of apps, photos, and files, since ROM switches and clean installs will typically wipe internal storage.


How to Flash the Firmware​


  1. Confirm in Fastboot that your phone reports thor as its product code, then download the needed ROM—for a pure stock base, use
    Code: 
    thor_images_OS1.0.16.0.ULACNXM_20241224.0000.00_14.0_cn_481a059036.tgz
    .
  2. Extract the
    Code: 
    .tgz
    file completely on your PC until you see the Fastboot ROM folder with the
    Code: 
    images
    directory and configuration files that Xiaomi Mi Flash Tool uses.
  3. Boot the Xiaomi 12S Ultra into Fastboot mode, connect it to the PC with a USB-C cable, and verify detection with
    Code: 
    fastboot devices
    or inside Mi Flash.
  4. Open Xiaomi Mi Flash Tool, select the extracted
    Code: 
    thor_images_OS1.0.16.0.ULACNXM
    folder, choose the preferred flash mode (keeping in mind that some modes will wipe all user data), and start the flashing process.
  5. Wait for the flash to complete and reboot the Xiaomi 12S Ultra; allow extra time for the first boot into HyperOS 1.0.16.0.ULACNXM after a clean install.

To see every step in detail, including screenshots and videos for Xiaomi Mi Flash Tool, refer to the full tutorial here:
How to flash Xiaomi Mi, POCO, and Redmi firmware files using Xiaomi Mi Flash Tool.


Frequently Asked Questions (FAQs)​


Firmware trackers and ROM indexes show that thor is the codename for the Xiaomi 12S Ultra (model 2203121C).

Yes, OS1.0.16.0.ULACNXM is listed as a HyperOS 1.0 China stable build for Xiaomi 12S Ultra running Android 14 with a December 2024 security patch.

It is a xiaomi.eu custom ROM built from the official China HyperOS 2.0.212.0.VLACNXM firmware for the Xiaomi 12S Ultra, providing multi-language support and Google services, but it is not an official Xiaomi release.

The public changelog only states a December 2024 security patch and improved system security; user reports suggest that while new builds can tweak stability, heavy camera and gaming workloads can still cause heat and throttling due to hardware limits.

Yes, many users unlock the bootloader, flash TWRP, and then install xiaomi.eu_THOR_OS2.0.212.0.VLACNXM_15.zip, but the process is unofficial, wipes data, and must respect bootloader and anti-rollback constraints.

Check that Fastboot reports
Code: 
thor
as the product name and that the ROM version codes (ULACNXM or VLACNXM) match known Xiaomi 12S Ultra China firmware branches listed on HyperOS/MIUI trackers.
 
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