[Xiaomi Mi 4C] PrivacyDefector:
A warm hello to my dear fellow Xiaomians!

I've been campaigning for Xiaomi phones for quite a while now, successfully convincing several friends of their unbeatable price-perfomance ratio. So far I've received very positive feedback. Unfortunately now that I'm trying to move past MIUI for the first time, it's giving me headaches. I was lucky enough to get a used Mi 4C with an unencrypted bootloader (fastboot oem unlock), but I can't for the life of me figure out how to flash TWRP. fastboot flash recovery always fails due to "size too large", even though the target reported max download size is around 760MB (given in bytes). I tried several versions of TWRP to no avail.

After abandoning the fastboot method I finally managed to flash the recovery image with the Flashify app (after successfully applying Kingo Root). Now the recovery appears to be gone completely since I'm unable to boot into recovery, and are instead presented with fastboot mode. This was the result after more than 5 hours of research and trial-and-error so you can imagine how frustrated I am. This device is listed as officially supported by LineageOS so of course I didn't expect it would be such a nuisance to flash.

My educated guess is that the device has been modified in a way that renders flashing impractical. Perhaps the partitions were resized improperly, but that would seem odd to me since the stock recovery was still present. There are a few more anomalies whose meaning I couldn't figure out on my own. The stock recovery presented me two systems to boot from. I have no idea how that feature is supposed to work, and couldn't find any information on it. The device has obviously been tampered with (as confirmed by fastboot oem device-info), as the MIUI version in about phone included the term decuro which I hadn't heard before. I quickly found out that decuro is an abandoned German MIUI project. Booting the second system would present me with what I believe to be the original MIUI 6 startup wizard. However it was completely unusable due to constant error messages of system processes. After my initial failures to flash TWRP I performed a full wipe. Everything appears to be the same (sans a bunch of bloatware), however the decuro reference in the about phone screen is now replaced with "BETA" (see screenshot below).

What also struck me is the differences in hardware to the official specifications you can found for this device online. XDA says about the Mi 4C:

"It comes in two variants, one with 16GB internal storage and 2GB of RAM, the other with 32GB internal storage and 3GB of RAM. Both are powered by a 1.82GHz hexa-core Qualcomm Snapdragon 808 processor"

Does that mean I have some kind of special variant? Does anyone have information on the specific model that I own? Please note also that when I tap System updates, an obviously modified Updater app is launched, again featuring the decuro label:

Before trying to flash anything I tried updating to the latest official MIUI ROM, assuming the bootloader was locked. I had to download the ROM manually since the Updater app says there are no updates. Trying to install the update package from within the app fails instantly, not specifiying what went wrong. So I renamed it to "update.zip" and moved it to the root directory of the internal storage, went into stock recovery and tried to flash from there. At 98% it would give me update failed due to signature verification. I'm now glad it didn't succeed because it would have locked the bootloader, and I prefer LineageOS anyway.

I hope someone here can shed some light on the whole thing. As of now I'm stuck with KitKat and no recovery, so any advice is highly appreciated.

UPDATE: Thread solved. I can't believe it, but this isn't a Mi 4C (libra). I checked the IMEI with Xiaomi's Product Authentication site because I was starting to consider that it might be a fake. Turns out it's genuine, and a Mi 4 (cancro)! The seller on eBay listed it as a 4C, the about phone menu said it was a 4C, and even Windows showed the device name as "Mi 4C". I don't get what this deception was supposed to achieve, but anyway. All working now.