[Redmi Note 9 Guides, News, & Discussion] vagelis199:
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How to install PixelPlusUI ROM on Redmi Note 9​

This guide will teach you how to install PixelPlusUI into Redmi Note 9 merlin or merlin Nfc version.

This is a more detailed and straightforward guide based on the official guide of PixelPlusUI found on their Github page here.

This guide can be applied to other customs ROMs* e.g Pixel Experience etc. ​

Yes, the process is exactly the same for pretty much any custom ROM you want to install to Redmi Note 9.

Installing Guide​

In this guide, I will explain to you how and why we follow certain steps, so you can clearly understand every step, process, and risk of installing a custom ROM into a Redmi note 9. And avoid breaking your phone, bricking/hard bricking your phone: no operating system or a possible way to recover it, lost IMEI: can't make calls or receive.

In this guide, I will not explain to you how to unlock your bootloader! you can find plenty of guides online on how to do it and it's overall an easy job.

Before you start you will need to have an unlocked bootloader to be able to modify your system files. Once you have an unlocked phone you can start with the process of Flashing* a custom ROM.

The steps we have to follow are​

--------------------------- Mandatory steps to be able to install a ROM, 1 - 7

1. Download Platform Tools*, A Custom Recovery*, and a modified VBMeta image, Mi-Flash to be able to downgrade MIUI, and the latest PixelPlusUI ROM which as of today is PixelPlusUI 3.9 for android 11 and PixelPlusUI 4.1 for Android 12.

2. Flash* recovery and VBMeta

3. Reboot into recovery

4. Backup IMEI

5. Downgrade your fastboot* into 12.0.3 version

6. Flash recovery and VBMeta

7. Reboot into recovery

--------------------------- Steps to install pretty much any ROM to Redmi Note 9, 8 - 11

8. Flash the latest firmware

9. Reboot into recovery

10. Wipe Dalvik/Art, Cache, Format Data

11. Flash PixelPlusUI ROM

---------------------------- Updating the ROM, 12 - 13

12. Update from 3.9 to 3.10.

13. Update to Android 12 with PixelPlusUI 4.1 (Optional) (Avoid for now cause it's unstable)

1. Once you have downloaded everything extract Platform Tools enter the folder where it contains all the necessary exes and run CMD inside this folder.

Turn off your phone, press the power and volume down button hold till your phone turns on, this will boot your phone into fastboot. Connect your phone via USB cable to your pc.

In CMD type "fastboot devices" without the annotations. it would output your phone right below with an ID and a fastboot label next to it.

if you are seeing "< waiting for device >" go to windows device manager, you'll find your phone in the other devices section with a yellow triangle. right-click it and click the first option to update the drivers, choose to select locally then Google => Android bootloader interface.

2. Now that we know fastboot is working and detecting our phone we have to flash the custom recovery.

copy the recovery file you downloaded, it should be an .img file, into the Platform Tools folder, in CMD now write "fastboot flash recovery recoveryname.img" without the annotations obviously, once its done, copy the vbmeta.img (might be named differently) also into the Platform Tools folder and write "fastboot --disable-verification flash vbmeta vbmeta.img" as vbmeta.img the file you just copied. if this throws an error do "fastboot flash vbmeta vbmeta.img" instead.

3-4. Now its time to backup our IMEI, if we don't back it up now, there's a change in the next step we lose access to make or receive phone calls, in case this happens we can flash back the IMEI and get it back to work. How do we back it up. While in fastboot, remove the usb cable, and turn off your phone, hold volume up and power till your phone turns on, wait till it boots into Recovery, if you accidentally boot normally into MIUI you will lose the recovery we installed before and it would roll back to stock xiaomi recovery, then you'll have to refollow step 2. Once in recovery, enter your pin and go to Tweaks, And tap the Imei backup, wait till its done, and then go back to the main menu, connect your phone via usb to your computer. your phone would pop up as a storage device, if nothing happens its because of the drives. go to windows device manager, you'll find your phone in the other devices section with a yellow triangle. right-click it and click the first option to update the drivers, choose to select locally then Google => Android ADB interface, Once it pop up enter into it and you'll find a folder called "imeibackup" copy that folder into your computer and keep it safe. this folder includes some partitions as img files and a zip file. the zip file is basically all the files archived into a single file, to be able to flash it later from recovery,

5. Time to downgrade your MIUI fastboot version, we have to do this, because if we don't downgrade we won't be able to install a custom ROM why? well, I actually down know, but pretty much flashing does nothing in the latest MIUI version 12.5 and so on, thankfully you can downgrade the MIUI version in the Redmi Note 9. The best version so far is the MIUI 12.0.3 and you only have to flash the fastboot image, The MIUI you gonna download has to be the same region as your phone e.g my phone is EU/Global i have to download the global fastboot image. if you miss-match them you won't be able to make or receive phone calls. Visit this page Visit this page find your regions "V12.0.3.0" MIUI version click on the very right "download" button, scroll down where it says "type:fastboot" bellow there a button "Download: Full ROM" the file ends with a tgz extension, extract the archive inside you'll find a folder named something like this "merlin_id_global_images_V12.0.3.0.QJOIDXM_20200807.0000.00_10.0_global" copy that folder into the root of your hard drive, rename it into merlin_id_global_images_V12.0.3.0.QJOIDXM

Install Mi-Flash, run Mi-Flash, click select and select the folder you copied into the root of your hard drive, on the bottom right corner flash_all_lock.bat change it into flash_all.bat this will prevent the bootloader from locking again, but it might destroy your IMEI partition, but thankfully we back it up in step 3-4. On your phone, while we left in recovery go to reboot => advanced => fastboot, once you are again in fastboot, connect your phone via a usb cable in to the computer in Mi-Flash press refresh, your phone will show up in the list, if not just follow again the drivers guide at the end of step 1. in Mi-Flash click flash next to refresh and wait till its done, the result should say success. Your phone will reboot and boot back to the old v12.0.3 MIUI version.

6-7-8-9. Now that we downgraded our phone is back to stock recovery and rom. we have to re-do some steps like installing the vbmeta and custom recovery.

Follow again the step 1 and 2. flash recovery and instead this time when flashing vbmeta.img just do "fastboot flash vbmeta vbmeta.img", reboot into recovery mode, by turning off your phone,

and then holding volume up and power till it turns on, now we are back into custom recovery we just installed again, in recovery now we have to flash the latest firmware of redmi note 9, this is necessary for PixelPlusUI to work properly. Download the latest firmware for your region from here, you'll get a zip file, copy the file zip into the platform-tools folder, open cmd in this folder and this time we have to sideload the zip via ADB. in your phone go to advance and then tap on sideload, tap the checkmark to start adb, on your pc in cmd you opened before type "adb devices" if it shows your device similarly as the fastboot devices step we did before you can continue if not, do the driver guide in step 3-4, once you ready type "adb sideload firmwarefilename.zip" replace firmwarefilename.zip with the firmware you downloaded name. once the sideload is done, click the X go to reboot=>advanced=>recovery, we have to avoid booting into miui now so we don't lose our custom recovery, this will reboot your back to recovery.

10-11. Now back in recovery go to wipe and tap the bottom right button Wipe with an arrow. when it's done, go to advanced and then sideload, click the checkmark,

copy the PixelPlusUI_3.9.zip into the platform-tools folder, in cmd you have open from before do "adb sideload pixelplusUI_3.9.zip" wait till its done sideloading.

once it's done, turn off your phone, and boot it normally, you will be greeted with the P logo of pixelplusui, set up your phone normally, if you see "no sim card please insert sim" its possible you flashed the wrong MIUI region or you lost your IMEI, you can flash the IMEI zip you backed up using the recovery's option of sideload or by using the flash option. if this does not fix it, redo all the steps but this time using mi-flash flash the right MIUI fastboot region and firmware region.

12. Updating PixelPlusUI from 3.9 to 3.10 which seems to be the last version before it got discontinued, in your phone, go to settings, system, update, download the update, once its done downloading, do not install it, close settings, hold the power button tap advanced => recovery, in recovery go to flash, go back in a directory and find the folder data/System Update, inside there you'll find a zip file called PixePlusUI_v3.10_something something.zip, flash that file without wiping anything, when it's done, go back and then go to wipe, tap advanced wipe, select only Dalvik/ART Cache and Cache so you don't lose any data. reboot, Done! Never update using OTA auto-update.

13. (For now avoid cause it's unstable) Time to Upgrade to Android 12 with the official build of PixelPlusUI version 4.1

Download the build, Using ADB sideload the latest official firmware, then reboot into recovery, format data and then install the ROM, you can copy it into the device or sideload it.

Every time you want to update or re-install a ROM (Any ROM) to your Redmi Note 9 you have to refollow the following steps:​

1. Flash the latest firmware, Reboot to recovery after flashing.

2. Wipe Dalvik/Art, Cache, Format Data ( Don't do it if you just upgrade )

3. Install desired ROM.

Platform tools is a suite made by google for developers, it contains adb and fastboot apps which help you with installing/wiping content and doing more development related stuff to your phone.

VBMeta.img is required to be flashed to allow installing custom recoveries if you don't flash it, it would reverse the installed recovery back to the default Xiaomi recovery.

Custom Recovery a custom recovery is basically a separate OS that you can use to factory reset your phone when you can't access the main OS, or in this case, install random tweaks and mess around with system files and partitions.

Flash or Flashing Basically installing system files, partitions etc. can be done using adb, fastboot or from recovery.

Fastboot Similarly to Recovery is an option where you can restore your phone when you cannot do using the recovery, which is why we use it to install the custom recovery in the first place.

Tips for people who want to mess around with custom ROMs.

Every time you want to re-install a ROM, you'll have to re-install the firmware, the best bet is the latest Xiaomi firmware. Also, formating data is necessary to avoid bugs.

Known Bugs:​

When the fingerprint sensor is touched it won't let you gesture swipe to close an app.

When the NFC is enabled there's a tapping sound on the microphone.