[Xiaomi Poco F3 / Xiaomi Mi 11X / Redmi K40] RollDload:
Hello everyone.

The purpose of this guide is to illustrate two methods to flash the stock rom on F3, both with the use of xiaomi flash tool (which for convenience I will call "miflash") and with cmd.​

Warnings!​

Before starting I would like to make one point clear, every moding operation involves risks that could lead to bootloop, softbrick or hardbrick of your phone, they can be caused by countless circumstances or actions, so you need the utmost attention and scrupulousness in performing certain operations.​

What I will describe I have tested it on my F3 and it works, in any case, ​

neither I nor the xda forum are responsible for any breakdowns on the phone caused by the operations described below!​

Having said that, let's start...

All you need is:​

Bootloader unlocked, using the official tool you find here

Latest version of miflash, which you can download from here;

SDK platform tools, which you can download from here;

Stock fastboot rom, which you can download from here, here or here.

Make a backup of your data because they will be deleted in the process!

Now that you have everything you need, follow the steps:​

1) How to flash a stock rom using miflash.​

Unzip miflash to C:\ ; [Only for the first time]​

Unzip SDK platform tools to C:\ ; [Only for the first time]

Unzip the fastboot rom in the miflash folder;

Rename the fastboot rom folder with a shorter name and no spaces like "V12.5.6.0.RKHEUXM";

Disable driver signature enforcement in windows 10; [Only for the first time. It is a temporary option that is reactivated the next time the pc is restarted]

Spoiler content hidden.

Go to the miflash folder in c:\, open it and search for XiaoMiFlash.exe, right click and start as administrator;

Click on the driver button at the top and then install (if a warning message comes out, install anyway); [Only for the first time]

Restart your pc; [Only for the first time]

Go to the miflash folder in c:\, open it and search for XiaoMiFlash.exe, right click and start as administrator;

Click on the select button at the top left and navigate to the fastboot rom folder in the window that opens, then press ok; (If you followed the guide it is located in C:\MiFlash20210226\namethatyougavetotherom);

Click on the clean all option at the bottom right;

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Now in the phone enable debug USB in developer option;

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Restart the phone in fastboot mode and connect it to a rear USB port or in any case to a USB 2.0;

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If the phone is recognized by miflash its code appears in the first row of the table otherwise click the refresh button at the top right;

Make sure clean all is selected and click on flash;

The flash lasts several minutes wait without touching anything;

Surely miflash at the end of the flash will give an error because the clean all option is selected and not blocking the bootloader at the end of the process it recognizes it as an error. Do not worry!!! it's normal;

If all went well the phone should restart by itself, (attention! the first start of the phone lasts several minutes stuck on the miui logo, wait until the configuration screen appears.

2) How to flash a stock rom using cmd.​

Small premise; You could easily use this method even just by starting the .bat file inside the fastboot rom, but if any problems should occur or at the end of the process the window would close immediately without giving you the time to understand what happened, while if you run the .bat file directly from the prompt (cmd) you have the possibility to check the whole flash process and see if any errors occur because the window will remain open anyway.
​

Unzip miflash to C:\ ; [Only the first time to install drivers]​

Unzip SDK platform tools to C:\ ; [Only for the first time]

Unpack the fastboot rom and move all content to C:\platform-tools;

Disable driver signature enforcement in windows 10; [Only for the first time. It is a temporary option that is reactivated the next time the pc is restarted]

Spoiler content hidden.

Go to the miflash folder in c:\, open it and search for XiaoMiFlash.exe, right click and start as administrator; [Only for the first time]

Click on the driver button at the top and then install (if a warning message comes out, install anyway); [Only for the first time]

Restart your pc; [Only for the first time]

Go to the start button with the mouse and click with the right button;

In the menu that will open click on command prompt (administrator) a cmd window will open;

Now in the phone enable debug USB in developer option;

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Restart the phone in fastboot mode and connect it to a rear USB port or in any case to a USB 2.0;

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Now in the cmd window you are in the path: C:\windows\system32. First we move to the platform tools folder and check if the pc recognizes the phone in fastboot (if you followed the guide it will be in C:\platform-tools) to move to the folder press this command and press enter:

cd c:\platform-tools

Now check if the pc recognizes the phone in fastboot with this command and press enter (The phone code should appear):

fastboot devices

If the code appears you can start the .bat file to start the flash, then type this command and press enter:

flash_all.bat

Spoiler content hidden.

The flash lasts several minutes wait without touching anything but you can follow the trend in case there are problems;

If all went well the phone should restart by itself, (attention! the first start of the phone lasts several minutes stuck on the miui logo, wait until the configuration screen appears.

I hope this guide can help you to get back or flash the stock rom.

Happy flash everyone!​