I have done this on two Xperia Z3 Compact phones this weekend in Bulgaria, bought from local mobile operator. I wanted the latest Sony firmware, so I did the following:
How to install the newest Android 4.4.4 for Sony XPERIA Z3 Compact D5803
There is information, that users who have unlocked the new Xperia Z3 Compact have found that low-light camera performance drops considerably. It turns out to be because of DRM in Sony's image signal processing.
When the bootloader is unlocked, the device loses certain DRM security keys. That means you can't purchase content from Sony's storefronts and a few licensed features won't work, but it apparently also means basic features of the phone are negatively affected. A Sony rep has confirmed that some advanced camera algorithms on the new generation of devices like the Z3 and Z3 Compact are protected by DRM. If you unlock the phone, those features stop working. Apparently that causes photos in low-light to be noisier and poorly balanced.
This isn't the first time Sony's bootloader unlock has come with some major drawbacks—unlocking past devices could actually break camera functionality (this was technically a bug). There have always been a few proprietary features that stop working, but the difference in image quality this time is allegedly noticeable.
Update: Sony has updated the text of the bootloader unlock warning on its website to be clear about the camera impact. It reads, "...the removal of DRM security keys may affect advanced camera functionality. For example, noise reduction algorithms might be removed, and performance when taking photos in low-light conditions might be affected."
Relocking your device bootloader will NOT get back the lost DRM Keys... Once locked, they will be lost forever! More info cant be found HERE
More detailed info and explanations can be found HERE
1) First of all, check your firmware version (if you already have the newest one, you do not need to download it, so skip step 3) and step 4), that are below. Just proceed with step 2) -> 5) from the PREPARATIONS (this) tutorial . Steps in the other tutrials are absolutely needed! Dont skip any of them!)
2) Download and install latest Flashtool from here (Latest Flashtool for Xperia Devices)
3) Download also latest Sony Original Firmware - 23.0.A.2.105 - Android 4.4.4 ( Mega Download ) for Sony XPERIA Z3 Compact
4) Paste the .ftf file downloaded in step 3 in folder „Firmware“ in your Flashtool installation folder. (for example for me is C:/Flashtool/Firmware)
5) Go on Sony Mobile site and download the Sony PC Companion. You must install it, because it installs some important drivers for your device. Since Sony stopped the Update Service application, now all the job is done from PC Companion.
a) After you installed the PC Companion, you must launch it and download the "Support Zone" addons from the main menu.
b) After that you must go in your Flashtool installation folder and find the Drivers folder. Go in it and install the Flashtool drivers for your device.
It is important to install Flashmode and Fastboot drivers with the driver for your device! Otherwise it will cause some problems during the flash procedure.
So now we're going into the real part of the things
2. BOOLADER UNLOCK
1) Go on Sony Mobile Developers website, register, enter your device IMEI and it will generate an unlock key for your device. Write it down!!!
1) Start Flashtool application and click on BLU button on the top
2) Turn off your phone and when Flashtool shows pop up window, connect phone to PC with holding volume down button
3) Copy the unlock key, that was given to you earlier from Sony Website to Flashtool window and than click unlock button
4) When you are prompted, disconnect your phone and connect the phone again, but this time with holding volume up button when Flashtool shows pop up window
5) Wait the unlock process to finish
6) Disconnect your phone and start it up. If it boots normaly, than all is DONE. Congratulations! You have unlocked your bootloader!
3. BOOTLOADER RELOCK
1) Download and install latest Flashtool from here (Latest Flashtool for Xperia Devices)
2) Start Flashtool and click on BLU button on the top
3) Turn off your phone and when Flashtool shows pop up window, connect phone to PC with holding volume down button
4) Just click on relock button and your bootloader is locked again
4. Flash Sony XPERIA Z3 Compact Latest Firmware - 23.0.A.2.105 - Android 4.4.4
1) Ensure yourself that you have the .ftf. that you downloaded in the PREPARATION process into the Firmwares folder of your Flashtool
2) Do not connect the phone to the computer yet. You must first open the Flashtool application, click on flash (the thunder) and choose Flashmode, than choose the firmware that you have downloaded and click ok.
3) Now turn off your phone and when Flashtool shows pop up window, connect phone to PC with holding volume down button
4) After few minutes of flashing, all is done!
The process is pretty slow! DO NOT DISCONNECT your phone during the proccess! Leave it still and for it to finish the flashing process! When it is DONE, Flashtool will say Disconnect and turn on your device (not a pop-up, just a line at the bottom of the other lines of words)!!!
If the device boots normaly, it should be factory reseted and it will boot slowly. Much slowly than normal.
Congratulations! You have the lates firmware from Sony!
5. Flashing ClockWorkMod Recovery
1) Download the kernel image with integrated CWM Recovery from HERE
2) Save the boot.img to folder of your choice
3) Open Flashtool, click on the Flash (thunder) and choose Fastboot. Choose "Choose file to flash" under the DooMLoRD "side" of the opened window. Then choose the folder, that you have saved the boot.img in and then choose the .img file itself.
4) Follow the instructions. There are two posibilities - the phone will reboot itself and go into Fastboot mode without you touching it OR you must turn-off the phone, hold the volume up key and connect phone to computer.
5) The flashing will finish verry fast. Wait for it and when it is done, disconnect you phone and turn it on. When Sony logo appears, start pressing the volume down button rapidly, until it enter the recovery mode. And you're ready to go!
You must ensure yourself, that you have falshed the kernel boot.img WITH the CWM Recovery!
1) Once you have flashed the kernel boot.img WITH the CWM Recovery download the latest SuperSU update.zip from: HERE
2) Save the downloaded .zip file on sdcard of device
3) Reboot into recovery and choose "Install ZIP from sdcard" and then "Choose ZIP file to install" (moving thru options is vol up / volume down keys; choosing an option is power button)
4) Choose the .zip file that you have downloaded on your sdcard and the installing should begin
5) After a while the installing should be finished you the recovery will bring you into the menu, that was just before the installation begin. You must choose "Go back" and then "Reboot"
6) The recovery will say you, that the root permisions must be fixed befor rebooting - choose ok / accept or fix (don't remeber what was the opiton really...)
7) If all is OK the phone must boot normaly ( the first time it will say "Upgrading Applications") and after that in the applications menu you must have an applicaion, named SuperSU. If you have it - Congratulations! You have rooted you phone successfully!
7. Installing BusyBox
It is highly recommended to install busybox after rooting!
You must just go to andorid play store and download the busybox installer. Once the installer is downloaded start it and choose to install busybox in /system/xbin. After the installation is done, reboot the device and you're done!
Special thanks (and apologize for using their files) to:
DoomLoRD - CWM Kernel, CWM Kernel Flashing and Rooting / BusyBox installing guide! - Sorry for using your files man, but I think that the users deserve at least one ALL-IN-ONE tutorial! Please, forgive me!
Unknown User from other website - Bootloader Unlock / Relock / Latest Firmware flash (with some additional explanations from me and my expirience! )