Install OkcarOS on
Xiaomi Redmi 3S

Mi8937

警告: The provided instructions are for OkcarOS 20. These will only work if you follow every section and step precisely.
Do not continue after something fails!

Basic requirements

Read through the instructions at least once before actually following them, so as to avoid any problems due to any missed steps!
Make sure your computer has adb and fastboot. Setup instructions can be found here.
Enable USB debugging on your device.
Make sure that your model is actually listed in the “Supported models” section here (exact match required!)
Boot your device with the stock OS at least once and check every functionality.
警告: Make sure that you can send and receive SMS and place and receive calls (also via WiFi and LTE, if available), otherwise it won’t work on OkcarOS either! Additionally, some devices require that VoLTE/VoWiFi be utilized once on stock to provision IMS.
LineageOS is provided as-is with no warranty. While we attempt to verify everything works you are installing this at your own risk!

Unlocking the bootloader

注意: The steps below only need to be run once per device. They require a machine running Windows 7 or newer.

警告: Unlocking the bootloader will erase all data on your device! Before proceeding, ensure the data you would like to retain is backed up to your PC and/or your Google account, or equivalent. Please note that OEM backup solutions like Samsung and Motorola backup may not be accessible from OkcarOS once installed.

Create a Mi account on Xiaomi’s website. Beware that one account is only allowed to unlock one unique device every 30 days.
Add a phone number to your Mi account.
Insert a SIM into your phone.
Enable developer options in Settings > About Phone by repeatedly tapping MIUI Version.
Link the device to your Mi account in Settings > Additional settings > Developer options > Mi Unlock status.
Download the Mi Unlock app (Windows is required to run the app).
Run the Mi Unlock app and follow the instructions provided by the app. It may tell you that you have to wait up to 30 days. If it does so, please wait the quoted amount of time before continuing to the next step!
After device and Mi account are successfully verified, the bootloader should be unlocked.
Since the device resets completely, you will need to re-enable USB debugging to continue.

Installing a custom recovery using `fastboot`

Download Lineage Recovery. Simply download the latest recovery file, named recovery.img.
Important: Other recoveries may not work for installation or updates. We strongly recommend to use the one linked above!
Download super_empty.img since your device uses retrofitted dynamic partitions.
Connect your device to your PC via USB if it isn’t already.
If your device isn’t already in fastboot mode, on the computer, open a command prompt (on Windows) or terminal (on Linux or macOS) window, and type:
```
adb -d reboot bootloader
```
You can also boot into fastboot mode via a key combination:
- With the device powered off, hold Volume Down + Power.
Once the device is in fastboot mode, verify your PC finds it by typing:
```
fastboot devices
```
If you don’t get any output or an error:
- on Windows: make sure the device appears in the device manager without a triangle. Try other drivers until the command above works!
- on Linux or macOS: If you see no permissions fastboot try running fastboot as root. When the output is empty, check your USB cable (preferably use a USB Type-A 2.0 one or a USB hub) and port!
Tip: Some devices have buggy USB support while in bootloader mode, if you see fastboot hanging with no output when using commands such as fastboot getvar ..., fastboot boot ..., fastboot flash ... you may want to try a different USB port (preferably a USB Type-A 2.0 one) or a USB hub.
Flash empty super image:
```
fastboot wipe-super super_empty.img
```
注意: If you get the following error: fastboot: usage: unknown command wipe-super, make sure ADB and fastboot are updated to the latest version. You need fastboot version 28.0.2 or greater.
Flash recovery onto your device:
```
fastboot flash recovery recovery.img
```
Now reboot into recovery to verify the installation. Do not reboot into the existing OS, since it will overwrite the recovery you just installed!
- With the device powered off, hold Volume Up + Volume Down + Power. When the screen lights up, release the buttons.
  
  注意: If you can’t power down the device, try long-pressing the key-combination (if any was used in the instructions above) until the device reboots and follow the instructions above
注意: If your recovery does not show the OkcarOS logo , you accidentally booted into the wrong recovery. Please start at the top of this section!

Installing OkcarOS from recovery

Download the OkcarOS installation package that you would like to install or build the package yourself.
- (Optionally): If you want to install Google Apps add-on package (use the arm64 architecture), you can download it from here.
If you are not in recovery, reboot into recovery:
- With the device powered off, hold Volume Up + Volume Down + Power. When the screen lights up, release the buttons.
Now tap Factory Reset, then Format data / factory reset and continue with the formatting process. This will remove encryption and delete all files stored in the internal storage, as well as format your cache partition (if you have one).
Return to the main menu.
Sideload the OkcarOS .zip package but do not reboot before you read/followed the rest of the instructions!
- On the device, select “Apply Update”, then “Apply from ADB” to begin sideload.
- On the host machine, sideload the package using: adb -d sideload filename.zip.
  Tip: Normally, adb will report Total xfer: 1.00x, but in some cases, even if the process succeeds the output will stop at 47% and report adb: failed to read command: Success. In some cases it will report adb: failed to read command: No error or adb: failed to read command: Undefined error: 0 which is also fine.
  
  注意: If installation fails with the following error: [liblp]Logical partition metadata has invalid geometry magic signature., make sure you did the previous step properly, and repeat it if needed.

Installing Add-Ons

注意: If you don’t want to install any add-on (such as Google Apps), you can skip this whole section!

注意: Add-ons aren’t signed with OkcarOS’s official key, and therefore when they are sideloaded, Lineage Recovery will present a screen that says Signature verification failed, this is expected, please click Continue.

警告: If you want the Google Apps add-on on your device, you must follow this step before booting into OkcarOS for the first time!

Click Apply Update, then Apply from ADB, then adb -d sideload filename.zip for all desired packages in sequence.

All set!

Once you have installed everything successfully, you can now reboot your device into the OS for the first time!

Click the back arrow in the top left of the screen, then “Reboot system now”.

注意: The first boot usually takes no longer than 15 minutes, depending on the device. If it takes longer, you may have missed a step, otherwise feel free to get assistance.

Get assistance

After you’ve double checked that you followed the steps precisely, didn’t skip any and still have questions or got stuck, feel free to ask on our subreddit or in #OkcarOS on Libera.Chat.

Install OkcarOS on Xiaomi Redmi 3S