Mine came carrier unlocked so any SIM card will work -- that's an absolute requirement for me as I travel a lot. On previous android phones, I would install a custom ROM (version of Android) in order to rid myself of the carrier and manufacturer bloat and add functionality. However, Sony's version of Android is streamlined and I like it so far. Plus, unlocking the bootloader (which is necessary to use a custom ROM), although easy to do, has downsides. It may void the warranty and more importantly reduce the quality of the camera and break anything requiring DRM. Plus custom ROMs may not have all the useful features Sony has, particularly power saving modes.
However, it's possible to root the phone without unlocking the bootloader. You'll have the stock ROMs and experience with a rooted phone that you can largely customize. In particular you can install the XPOSED framework to install XPrivacy, which like Privacy Guard in CyanogenMod allows controls over app permissions. It also allows me to run apps like AirAudio that require root. And at a pretty basic level, with root I can back up the phone.
My Z1 Compact was loaded with Android 4.4.4 Kitkat.
This guide will root the phone and upgrade it to Sony's stock Android 5.1.1 Lollipop, without wiping any software/settings.
** UPDATE 2/14/2015 with the latest versions of apps and how to root if you're already on Lollipop (5.*) **
** UPDATE 12/7/2015: it is possible to upgrade to the latest firmware version 14.6.A.1.236 using this procedure (in step 7). If you already had upgraded to rooted 5.1+ you can just do step 7+ to get the latest firmware. This update includes the stagefright 2.0 fixes. (If you use Xposed be sure to get the latest version of that as well.) **
- Download the latest flashtool software and install it. (You can get a head start by now downloading the firmware needed in step 7.1)
- Once installed, go to flashtool's drivers subdirectory and run the drivers installation found there. Choose flashmode and flashboot, along with drivers for the Z1C. It'll likely take a few minutes.
- My phone shipped with build number 14.4.A.0.157 of Kitkat (you can see this under Settings->About Phone). Unfortunately the "one-click" root solution doesn't work for this version or any other above 14.4.A.0.108. Instead we'll downgrade to .108 and root. If you're already at .108, skip this step.
- Depending upon what version of Android your phone came with:
- If you have KitKat (Firmware 14.4.* / Android 4.4.*) then you can downgrade the kernel (only). Download the zip file from this guide and unzip the .108.ftf file.
- If you have Lollipop (Firmware 14.6.* / Android 5.*.*) then you must install the whole .108 firmware. This can be found here. You may have to use File->Switch Advanced, and select to wipe userdata (You will lose your user data in this case!) for step 4, in order to be able to boot.
- Put the .ftf file into the .flashTool/firmwares directory under your home directory (Eg, C:\Users\username\.flashTool\firmwares).
- Enable developer mode by tapping 7 times on the Android Build under Settings -> About Phone. Then under Settings -> Developer options, enable USB debugging. And under Settings -> Security, enable Unknown Sources.
- Run Flash tool; click the lightning button, select Flashmode. Select the A.0.108 kernel firmware file and hit Flash. Then follow directions to power down and attach your phone to the computer, while holding the volume down button until the flash process begins.
- Once complete, unplug the USB cable, close flashtool, and turn on the phone.
- Root the device using "one click" solution from here (in windows, the tool included in the zip from last step should work as well but is older).
- Ensure USB debugging and unknown sources remain enabled, as above.
- Run install.bat in windows or install.sh on mac/linux.
- Wait until it tells you to connect the device via USB, and then do that.
- Now, wait until it tells you "Device Rooted", dismissing any prompts on your phone if they appear.
- Now that you can, backup using online nandroid backup software (get and install it and required BusyBox from the Google Play Store). Save all backups to external SD and/or computer. This includes the TA partition that is wiped if you bootloader unlock. To just backup that critical partition (needed to allow you to restore stock at some point if necessary), there's also this tool.
- Install dual recovery using installer. A recovery is like a custom BIOS that enables easier flashing of ROMs and recovery from errors. With this package you get two; you can open clockworkmod recovery by pressing the up arrow after the green/purple light flashes during bootup, and the TWRP recovery by pressing the down arrow. Sometimes one is needed rather than the other.
- Download installer Z1C-lockeddualrecovery2.8.25-RELEASE.combined.zip (or newer) from here. This version can be used both to install initially and later to flash.
- Unzip it (but keep the .zip for later) and run install.bat/install.sh. Choose (2) rooted with SuperUser. Connect phone when prompted and wait until complete. Reboot phone.
- Upgrade to Kitkat using this guide to create a pre-rooted firmware.
- Run flashtool to download the firmware version you want (14.6.A.0.368 or 14.6.A.1.236 either customized for your region or generic) by clicking the XF button, finding it and downloading by clicking its name on the far right, selecting to unpack automatically. This takes a while as it is big. Once complete, it will be in your .flashTool/firmwares directory.
- Download SuperSU
- Download PRFCreator, unzip it and run it.
- Choose the FTF file you just downloaded in flashtool.
- Choose the SuperSU binary you just downloaded.
- Choose the Z1C-lockeddualrecovery2.8.25-RELEASE.combined.zip you downloaded previously for the recovery.
- Select all of the checkboxes except "sign zip" (including "legacy mode" which is below sign zip) and click "Create". This will take a while.
- It will appear in the PRF directory as flashable-prerooted.zip. Copy this to the phone/SD card.
- Install the pre-rooted firmware.
- Reboot your phone into TWRP recovery by pressing the down arrow after the green/purple light blinks during bootup.
- Go to wipe, advanced wipe, choose dalvik cache and cache and wipe (maybe unnecessary but doesn't hurt).
- Then return to main menu and install. Find the flashable-prerooted.zip file and install it.
- Once again wipe dalvik and cache.
- Then reboot to system. It will take a while as the new OS is configured and apps are optimized. Don't fret, all this optimizing means the apps will run faster later on. The NFC firmware will also be updated.
- Done! You now have a rooted phone with a locked bootloader running Lollipop 5.1.1!
- Via the browser on your phone, download and install the latest XPosed Installer app from http://bit.ly/1LodTO5 (I used 3.0-alpha4). It won't work yet.
- Download the latest Xposed framework zip to your phone from the same link. The Z1Compact requires the 32-bit ARM version. For Android 5.1.* it's SDK22 (if you updated to 5.0.* instead, use SDK21). I used xposed-v80-sdk22-arm.zip. (SDK23 is for 6.* which likely won't be available on the Z1 compact).
- Reboot the phone into TWRP recovery by hitting the volume down button once the green/purple LED lights up during boot. Install the xposed SDK file zip you just downloaded and reboot to System. The Xposed Framework is now installed, the next bootup will take a while.
- On your phone, Now visit http://bit.ly/1QfkTxT and download and install the latest XPrivacy APK. Reboot the phone a second time.
- Go into Xposed installer, under modules, enable XPrivacy. Reboot the phone.
- XPrivacy can now be configured.
Thanks to: SlikToxic, WaleDac, Jamal, zxz0O0, and Muuuly who first found the components of this solution. And to all the linked app developers!
* Really appreciate making your purchase through these links as I'll get a small commission at no cost to you.