[HTC One Mini] windovv:
Greeting from Vietnam, and sorry for my English ;)

So, you dont want to wait the official-update from your carier/country, you got the OTA file from somewhere else, i'm gonna show you how to flash it, step by step with some stricks

This might works with other phones (I think), but in this guide we'll doing stuffs with HTC One Mini Android 4.2.2, flashing 4.3 OTA file

Before you do anything, i suggest you should do a nandroid backup, so you can get back your official rom any time. This is very important, please google for it

(For those who dont know: to do this, you'll need Unlock bootloader, then installing a custom recovery, i recommend TWRP instead of CWM, i've got error with cwm once -> Get into Recovery Mode -> Backup -> Save it to your computer)

I've googled and tried some other ways to upgrade the phone, but it was not work, like:

Well, that's the idea. But right after your download is done (in your phone), it turns out error: "Variant system version", saying your phone has been modified, and end up by delete the OTA file

Let's get started

1. Requirement, Your phone must be:

Disabled Fast Boot:

Enabled USB Debugging:

Unlocked Bootloader

Got the S-Off (For HTC phones, to: be able to write to /system)

Installed a custom recovery (recommend TWRP)

The guide can be found at here: http://xdaforums.com/showthread.php?t=2365506

2. Download the OTA file

You can use any OTA files, like the EU, the international,...

For HTC One mini, 4.3 OTA file can use this: OTA_M4_UL_JB43_SENSE55_MR_HTC_Europe_2.12.401.1-1.32.401.2_release_342200vz5jcl35ysxswchv.zip by http://xdaforums.com/showpost.php?p=48404636&postcount=1

3. Flash the firmware

Extract the OTA file you'll get firmware.zip

Make sure you already got the fastboot.exe, adb.exe, AdbWinApi.dll, ... files -> Move all these files + the firmware, the OTA file into a folder like: D:\htc

Reboot your phone into Fastboot USB Mode

Make sure your phone is recognized by fastboot and adb, to check:

In case you got error "Device not found" with adb: turn the phone into Recovery Mode, it will fix this, so you can do adb push, shell...

Relock the bootloader, so we can flash the firmware update:

Reboot to OEM update mode:

Flash the firmware.zip:

Unlock Bootloader from http://htcdev.com, install the TWRP Recovery again

Now your phone is wiped, the /sdcard/ folder is empty

4. Make the OTA Flash-able file

Download the sample.zip file at here, we'll rename it to: OTA-4.3.zip, see How to make a flashable zip at here: http://xdaforums.com/showthread.php?t=2163974

Open OTA-4.3.zip with winrar or 7zip, you'll see 2 folders: META-INF/ and system/ . We're going to put data from the OTA file into this zip file (Notice that the system/ folder is empty)

From the extracted OTA file that you've downloaded (OTA_M4_UL_JB43_SENSE55_MR_HTC_Europe_2.12.401.1-1.32.401.2_release_342200vz5jcl35ysxswchv.zip) copy 2 folders: system/ and patch/ into OTA-4.3.zip, just drag and drop them to opened OTA-4.3.zip (by winrar), hit OK in the winrar popup

--> You might wonder why we're doing this: Why we put 2 folders from OTA_M4_UL_JB43_SENSE55_MR_HTC_Europe_2.12.401.1-1.32.401.2_release_342200vz5jcl35ysxswchv.zip to the new, almost empty OTA-4.3.zip; instead of delete all other files, folders from OTA_M4_UL_JB43_SENSE55_MR_HTC_Europe_2.12.401.1-1.32.401.2_release_342200vz5jcl35ysxswchv.zip

--> The anwser is: i have no idea, the second way just doesn't work, i tried

5. Flash the OTA Flash-able file

Copy the OTA Flash-able file (OTA-4.3.zip) into your phone, your phone can not boot up now, so we'll use adb push command

Now simply Install Zip from recovery:

Reboot the phone, if everything goes well, it's showing a progressbar of the Apps installing

You're now in 4.3