POCO C40

Parent directory/

 

 

FIRST IMPRESSIONS:

 

I bought this phone back in november 2023 sealed with 1 year warranty for 100 euro. I set it up, set up bootloader unlock, and immediately debloated it and after deep debloating I was very disappointed with performance, it was way too clunky to use.

 

MODDING:

 

Mi Unlock tool told me to wait 360 hours to unlock the bootloader for no reason (and meanwhile i factory reset it too, while the counting kept going i waited just for it to say device not activated so i had to wait 360 hours again :DDD).

 

Meanwhile in Android the phone shows up fine in ADB, in fastboot it detects itself as a "USB Download Gadget" so every time i plug it into my desktop I have to manually set up the driver for it.

 

Otherwise flashing diffrent firmwares and GSIs proved to be extremely easy.

 

As of January 2025, recently 2 things released on the 4pda forum in MIUI firmware section.

 

https://4pda.to/forum/index.php?showtopic=1055075

 

First is "Engineering Firmware". ❗VERY IMPORTANT❗ First I am going to say, If you flash it using Mi Flash Tool, even if you select "Clean All", it will flash and when you do "fastboot getvar all" it will say "unlocked: no", but I heard the lock is fake and it's made like that for test purposes. Mi Flash Tool will let you flash something else, but I to avoid bricking it I flashed signed MIUI 13 Image, and than even if you do "clean all" the bootloader gets fully locked. When I tried to log into Mi Account, enable "USB Debugging", and try to unlock the bootloader using "Mi Unlock Tool", it either gives me "Can't get info" or "Request Parameter Error". Further info is available at the bottom of the page.

To put it simply it has JLQ boot splash, AOSP recovery, the OS itself is AOSP with all the test apps, it is in chinese and in settings there is no option to change language, but that is fixable by doing:

 

adb shell "setprop persist.sys.language en; setprop persist.sys.country US; stop; start

 

I do not know how safe it is to use because it is made for testing, It runs snappily, low RAM usage, but I have not tested smoothness and battery life much. It is smoother than factory MIUI even if it does have tiny stutters.

 

Second firmware is Frost Repack 13.0.2TW (Also from 4pda):

 

When flashing in Mi Flash Tool, you have to rename “flash_all_windows.bat” to “flash_all.bat” of course DO NOT FORGET to change bottom right settings to “Clear all”. Otherwise, haven't tested much, buttery smooth, high ram usage, and if I try disabling Google Play Services, there is infinite spinning circle and Logcat is going all crazy about it. Someone please make a no google repack for low ram variants. Still, amazing work by whoever made it.

 

GSI BUGS

 

Pretty much all functionality works, except:

 

1. Rapid battery drain on screen off in Android 11 (fixed in Android 12, but 12 is a bit slow so go for at least 13)

 

2. Bluetooth headphones (all android versions)

 

3. Screen recording in Android 12 and above

 

4. Bluetooth not working but fixable in phh settings

 

5. On Android 13 and above video colors are completely broken on screen

 

6. Brightness slider needs to be fixed by enabling "Force Alternative Backlight Scale"

 

7. On Android 15 *maybe* the SD card will say that it needs to be formatted, I deleted all files from it and it worked

 

8. Status bar icons are large which is easily fixable by doing:

 

adb shell pm uninstall --user 0 com.miui.systemui.devices.overlay

 

GSI ADVANTAGES (only 4 but MAJOR advantages):

 

1. Loads everything much faster

2. MUCH smaller RAM usage (if you have 3GB model and want to do multitasking, DO NOT INSTALL GAPPS)

3. The newer Android version, the less stutter (Android 15 is literally usable apart from all the mentioned bugs)

4. 0 BLOATWARE

 

Recommended GSI: LineageOS by AndyYan arm64 bvn

 

Conclusion: I am sorry if you got this phone for retail price thinking it is a good deal. While for recommended:

 

If you priotitise multitasking and do not mind the bugs mentioned Android 15 is the way to go.

 

If you prioritize stability and smoothness, while not needing multitasking Frost Repack is the way to go.

 

UNLOCK BOOTLOADER AFTER ENGINEERING FIRMWARE IF YOU CANNOT UNLOCK IT USING MI UNLOCK:

 

Since this has a odd SOC I could not use "MTKClient" to unlock it, so I had to download the zip for Termux-MIUnlock:

 

https://github.com/RohitVerma882/termux-miunlock

 

, install the included apk on any phone and log into Mi Account, copy the "DATA" pile of texts and numbers and paste is somewhere where you can easily transfer it to another machines. Than I rebooted the POCO into bootloader mode, did

 

"fastboot getvar product" (product name is frost)

 

"mi-fastboot oem get_token" (to get "phone's internal TOKEN")

 

, than in Linux  with Java installed, I had to run

 

"chmod +x get_token.sh" and "./get_token.sh --region=global --product=frost --token=TOKEN DATA" (TOKEN is phone's internal TOKEN and DATA is the thing you got from that apk). It will generate the final needed token and than you can use to unlock the bootloader. You have to do (FTOKEN is placeholder for the final token):

 

"echo FTOKEN | xxd -r -p > token.bin"

 

"fastboot stage token.bin && fastboot oem unlock".

 

After that the bootloader should be unlocked. The data will be erased too.