Upgrading the POCO X3 NFC

Time to upgrade the POCO X3 NFC. Xiaomi is not rolling out any major version updates for this model.

1. If using MIUI, update to the latest verserion 12.1 and backup your stuff
2. Unlock the bootloader. This can take a few days. Download the Mi Unlock tool. Add your Mi Account to the phone.
3. Enable unlock in the Developer Settings. Run the Mi Unlock tool to start the countdown. Note there is no need to wait for 168 hours or 7 days. Just backup and regularly check in.
4. While waiting for the unlock, download the Nitrogen build, NikGapps Core version and MIUI ROM zip version into a SD card. The MIUI ROM is only for emergency use. Link
5. Download Brigudav’s TWRP onto the PC. This can be found on the first page of ArrowOS thread. This version can decrypt the storage and write to it. Link
6. Once the bootloader has been unlocked, at the boot screen, there is an unlocked padlock at the top of the screen.
7. Boot to bootloader with the rabbit icon. On the PC, check if the phone is visible “fastboot devices”
8. Use the PC to flash Brigudav’s recovery “fastboot flash recovery <recovery filename.img>”
9. While in Fastboot, reboot the phone to Recovery. Failure to do this will result in the TWRP being overwritten by stock revcovery.
10. In Recovery, format storage and user data.
11. Flash Nitrogen and NikGapps Core from the External SD card.
12. Restart the phone and wait.
13. There is no setup process. Core Gapps.
14. If there are dual SIMs, assign the SIM to receive Calls and SMS. Failure to do so would not be possible to do 2FA
15. Go to Settings, Accounts to add Google account and install from Play store.
16. Add a PIN for the lockcreen or Recovery won’t be able to read the storage.

Edit: 10 Aug 21

Some things to note. I have encountered some serious problems. When I used my Telco’s SIM switching code, the 2FA SMS never arrived and unknown number calls, the phone rings without any screen popup for the incoming call. NikGapps Core version is bare Google Apps. It also replaces the AOSP Phone/dialer and Messages. I suspected this is a problem and with the SIM switching code

In the end, I did a full reset and flashed the full version of NikGapps, while keeping the AOSP apps (option 2). Physically moved the primary SIM from the backup phone to POCO to get the calls and SMS.