[Xiaomi Mi Mix 2S Guides, News, & Discussion] underlines:
In the original Mi Mix Forum we had a one-in-all thread for all new users, so I try to continue it here.

I will try to mention all people from who I take sources from. If I forgot anyone, please don't hesitate to tell me.

If you have change requests or useful additions, I will try to update the original posts ASAP.

Change log 2018-08-16 03:30 AM UTC

+ Updated: MIUI 10 china & global beta links
+ Added: Google Maps Location Sharing & Timeline on Chinese ROM
+ Updated: Working GCam links

Chat Group

Get live help and discuss topics around Mi Mix 2S in our Telegram Group: MOD EDIT: Telegram link removed, read the STICKY!

Available ROM & Download Links

The variants sold outside of China come with the Global ROM including Google Apps.

For devices that have the Official Chinese ROM, it's only possible to flash the Official Global ROM after you unlock your device due to region mismatch.

OTA or recovery zips can be flashed in the official MIUI updater app if it matches your region) or if you're unlocked, you can flash through TWRP whatever you want.

Fastboot ROM can be flashed by using fastboot or the XiaoMi Flash Tool.

ROMs:

Recovery can be flashed through the Updater app on your phone (if locked, china can only flash china, global can only flash global) or better through TWRP Recovery (if unlocked, can of course flash any region over any).

Fastboot can be flashed by connecting your phone through USB and use XiaoMi Flash Tool or fastboot.

Custom ROMs can be flashed by TWRP (if unlocked)

MIUI 9.5 Official Download Links on miui.com (Chinese Stable/Developer, Global Stable/Developer)

Recovery latest

Fastboot latest

MIUI 9.5 Global Stable (leaked):

Recovery 9.5.19

Recovery 9.5.18

Recovery 9.5.4

Fastboot 9.5.4

MIUI 10 Global Closed Beta, Android 9 (leaked)

Recovery 8.8.7

MIUI 10 Global Closed Beta, Android 8 (leaked):

Fastboot 8.6.26

Recovery 8.6.14

MIUI 10 Chinese Beta, Android 9.0 (leaked)

Recovery 8.8.15

MIUI 10 Chinese Beta, Android 8.0 (leaked)

Recovery 8.7.2

Fastboot 8.6.21

Recovery 8.6.13

Recovery 8.6.12

Recovery 8.6.11

Recovery 8.6.6 *relocks bootloader, flash root/magisk or unlock again (you'll loose /data)

Recovery 8.6.5

Recovery 8.6.4

Recovery 8.5.31

MIUI 9.5 xiaomi.eu Custom ROM:

Recovery latest

Official Android P preview from Google (pure AOSP):

System Image

AOSP Custom ROMs

Mokee

Lineage Treble

Available TWRP recoveries & Download Links

TWRP by xiaomi.eu and miuiItalia

The first versions are from xiaomi.eu and miuiItalia and aren't able to read encrypted internal storage. If you want to flash something with this TWRP you need to format your internal storage then copy the file over in MTP mode and flash it. So you loose your storage all the time. No problem when you want to cleanly flash new ROMs, but annoying when you just flash magisk, mods and other things.

Download TWRP polaris by xiaomi.eu

Download TWRP by miuiItalia

TWRP by notsyncing

notsyncing's version is able to work with encrypted storage. You need to enter your pin or draw your lock pattern in order to work. Switching between different ROMs like Chinese/Global/Custom you most probably still need to format your /data, but when you stay on the same ROM no need to wipe or format.

Thread

Guide: Install Google Apps & Contact Sync on Chinese ROMs

Chinese ROMs don't contain Google Apps. Especially if you didn't unlock your phone you probably want to install Google Apps and Framework:

Download the Oreo Google Apps package: https://androidfilehost.com/?fid=818222786056028173 and extract it on your phone

Install every APK from 1-6 without opening them after installation!

Install 8.0-Oreo.com.google.android.gsf_8.0.0-4147944-26_minAPI26.apk

Don't inistall the remaining two APKs

Download and install the updated contacts sync 8.1.0 APK: https://www.apkmirror.com/apk/google-inc/google-contacts-sync/google-contacts-sync-8-1-0-release/google-contacts-sync-8-1-0-2-android-apk-download/

Go into Settings > Installed apps and find all Google Apps in the list. Select each of them and turn on Autostart Permission. Additionally go into Permissions and enable all permissions in there. Again: Do this for all Apps you've just installed or that have the name Google or Contacts or Calendar in it.

Reboot your phone

Login to your google account, by opening Settings > Sync > Add Account > Google

Guide: Install Global ROM (leak)

If you're on Chinese or xiaomi.eu ROM and you want to flash the official Global ROM that has been leaked:

Unlock bootloader

Download Global V9.5.18.0.ODGMIFA from above

Boot phone into fastboot, open fastboot console on your pc, connect phone via USB with your pc

download and extract official twrp recovery for mix 2s and name the file recovery.img and copy it onto C:\

fastboot boot recovery.img

wipe > advanced > dalvik cache, system, data, internal storage, cache

copy V9.5.18.0.ODGMIFA zip and region fix onto your phone (may not be necessary with global device, and/or with newer global ROM leaks. try without the fix first)

twrp: install V9.5.18.0.ODGMIFA zip

twrp: install region fix zip

reboot and complete setup of your phone

For magisk see below

Guide: Install MIUI 10 leak

phone: boot to fastboot

pc:

fastboot boot twrp.img

phone: wipe data, system, dalvic, cache

phone: format DATA

phone: reboot phone into fastboot

pc: fastboot boot twrp.img

pc: transfer miui 10 zip to phone memory

phone: install miui 10 zip

phone: reboot to miui 10 setup device wizard

phone: in case your device is bound to a xiaomi ID, enter your password

phone: complete MIUI 10 setup

phone: download form apkmirror and install:

Magisk

Info: info: may not work if you have the chinese 6GB model instead of the global model, but always works on the 8gb model

phone: reboot to fastboot

pc: copy magisk 16.4 install/uninstall zip to phone

phone: install magisk

reboot

Guide: Install official Android P developer preview

Google announced the Android P preview officially for the Mi Mix 2S as shown here: https://developer.android.com/preview/devices/

Requirements:

Unlocked bootloader

ROM: http://bigota.d.miui.com/8.5.3/polaris_dp_global_images_8.5.3_20180503.0000.00_9.0_ef2f024b87.tgz

Setup after first boot needs to be completed in Chinese. Then afterwards changing the language to English is possible

Steps to install: Download Android P for Mi Mix 2S: http://www.mi.com/en/androidppreview/

Guide: Unlock bootloader

On your phone, login to your Miui Account, if you don't have an account, create one. That's under Settings > MI Account

Enable developer mode on your phone, under Settings > My Device > All Specs > Tap on MIUI version 5 times until the toast notification tells you that you're a developer

Go into Settings > Additional Settings > Developer options > Enable: OEM unlocking, then go into MI Unlock status and "Add account and device". (If you get an error messages, you need to use a VPN app and connect to a city in Mainland China, like Beijing)

Download and run http://en.miui.com/unlock/ the unlocker app on your computer, login with your MI Account. The first time you may have to apply for Unlocking permissions with your MI Account. The SMS confirmation code they send you may take several days to arrive. Please be patient and don't try to unlock your device before.

After you got your SMS confirmation code, enter it in the unlocker application on your computer and connect your phone via USB

Try to unlock your phone.

Sometimes Xiaomi will now force you to wait for up to 360 hours until you can try again to unlock. This is annoying, but you have to wait. Otherwise your account may be blocked.

Guide: Flash any Treble ROM

Download any Treble ROM:

https://xdaforums.com/project-treble/trebleenabled-device-development

https://xdaforums.com/project-treble

Requirements:

Unlocked bootloader

Be on Global or Chinese official stable ROM, flash it through XiaoMiFlasher and download the fastboot ROM from mi.com if necessary

Minimal ADB & Fastboot installed on your Windows computer

Download the ARM64 NANO OpenGApps for the exact Android version your Treble ROM uses: https://opengapps.org/

Optional: Download Magisk 16.4 and Magisk Uninstaller

Perform a factory reset on your device. You have two options here:

Open the settings app on your phone and look for the factory reset option.

Boot your phone into fastboot

With your device connected to your PC start the Minimal ADB & Fastboot console

Enter a command in the following format:

fastboot flash system

having a space at the end, so it's fastboot flash system(SPACE) and drag and drop your Treble img file with your mouse from an Explorer window into the cmd console

Example:

fastboot flash system C:\Users\Superman\Desktop\Mix2S\system-arm64-aonly-gapps-su.img

Push enter, and allow the image to flash, it could take a few minutes.

Once it has completed, reboot your device into fastboot then (WARNING: THIS WIPES EVERYTHING) enter

fastboot -w

from your computers command prompt window.

Reboot

Optional:

You can flash TWRP and then flash GApps and or Magisk if you want. The DM-Verity check may prevent the phone from booting, so by flashing Magisk DM-Verity check should be disabled and your phone should boot.

Guide: Flash TWRP Recovery and Custom ROM

Download TWRP for Mi Mix 2S above

Extract the img file of the TWRP zip you've downloaded, into C:\ and name it recovery.img

Turn off phone

Press Volume Down + Power button until phone boots into fastboot mode

Download and install latest Minimal ADB and Fastboot from here https://xdaforums.com/showthread.php?t=2317790 on your windows computer

Connect your phone with the USB cable

Open a CMD window on your windows computer (Press CTRL+R enter cmd, press enter)

enter the following command and press enter: fastboot flash recovery C:\recovery.img

enter the following command and press enter: fastboot boot C:\recovery.img

Wipe /data partition

Copy the ROM zip file to the internal storage of your phone

Install the ROM zip

Reboot

done

Guide: Install Magisk

More information on http://en.miui.com/thread-2449455-1-1.html

For Official Global ROM (not xiaomi.eu) I can confirm this works (safetynet passed):

Chinese / Global / Beta + M1803D5XA + Magisk = OK

Chinese + M1803D5XE + Magisk = OK

Chinese + M1803D5XE + Magisk = OK

xiaomi.eu + M1803D5XE + Magisk = OK

Global + M1803D5XA + SR-SuperSU-v2.82-SR5 = OK

How to flash Magisk the common way

Use the modified twrp with working partition decryption

Unlock your bootloader

on PC: fastboot boot recovery.img

in TWRP: Install your ROM (example Global V9.5.18.ODGMIFA)

If you want to flash global on a chinese device, in TWRP: install region fix otherwise go to next step

on Phone: Boot and complete MIUI setup

on PC: fastboot boot recovery.img

in TWRP: enter your password to decrypt storage

in TWRP: install Magisk-v16.4.zip

Reboot

Guide: Pass Safety Net with Magisk

Install MagiskHide Props Config in MagiskManager Modules

Reboot phone

Install Terminal Android, and start it.

Give it root permissions

type in the terminal window:

su
props
1
fingerprint

use the fingerprint:

Xiaomi/polaris/polaris:8.0.0/OPR1.170623.032/V9.5.15.0.ODGCNFA:user/release-keys

And boom, pass safetynet after a reboot

Enable Google Maps Location Sharing & Location History on Chinese MIUI ROM

You need Magisk properly installed on your ROM and then download & install the module: Unlock CN GMS

Google Camera with HDR+

Some modified versions of Google Camera may allow to use HDR+ with the Mi Mix 2S. For some these may work:

defcomg-fix_OP6v0.3_MGC_5.1.018_FINAL_3.4A.apk

As the modders keep creating new fixes, you should try out new versions from here regularily and see if HDR+ works and the portrait camera works.

Original thread: Mix 2S Google Camera