[Xperia Z3 Tablet Compact Q&A, Help & Troubleshooti] Samavb:
Detailed procedure I followed to root my Sony Xperia Z3 Tablet SGP 621 (lollipop)

Disclaimer: "Before you do any thing please follow this thread & Backup your TA key first using this thread " or you will lose DRM keys forever.

Here is what I did. Sorry for making it so long.

MY PC - Windows 7 x64 SP1

My Device - Sony Xperia Z3 Tablet Compact.

1) Install the flashtool on your PC. The one which I used was flashtool-0.9.18.5-windows.exe file.

Once downloaded install the flashtool to lets say C:\Flashtool.

In that folder go to "drivers" folder and install the file.

This is extremely important.

Please refer to the "driver installation 1.jpeg" and "driver installation 2.jpeg" in the attachments below on what to select during installation.

Once you select those three options hit "install".

Now you have flashtool installed on your PC.

Go to "Start" -> type " Flash and you will have two options if you are having 64bit windows OS. Select "Flashtool 64".

For better understanding please check the "Flashtool 64.jpeg" in the below attachments.

When you open flashtool software it will ask you to move the firmware ftf file which is there in C:\Flashtool\firmwares to C:\Users\abcd\.flashTool\firmwares

abcd is my username in the PC I used.So you have to navigate to similar path in your PC.

In the same location paste your Sony lollipop firmware SGP621_23.1.A.0.690_NOBA.ftf

flashtool is ready for use.

2) On your Sony xperia z3 tablet. Go to Settings -> Developer settings -> Check USB debugging and unknown sources.

Switch off the device.

Now press "volume down" and connect the Sony Xperia Z3 tablet to your PC.

Select the SGP621_23.1.A.0.690_NOBA.ftf in the flashtool and flash it.

This might take roughly 5 to 10 minutes but it will complete for sure.

Reboot the device and go inside the Settings -> Developer settings -> Check USB debugging and unknown sources.

3) Unlocking bootloader (Do this step ONLY if you have backed up your TA keys or Do NOT attempt this)

Open the phone dialer on Sony Xperia Z3 tablet and type *#*#7378423#*#* .

Go to Service info > Configuration > Rooting Status.

It should say bootloader unlock allowed: yes

You will need IMEI number of your Sony Xperia Z3 Tablet Compact.

Either you can check on your Box or type *#06# and you will get your IMEI number.

Write this down somewhere.

Go to this site http://developer.sonymobile.com/unlockbootloader/unlock-yourboot-loader/ and follow the instructions to get your unique unlock code.

Once you go through each and every step in that sonymobile site you will get the code and further instructions in your email.

For better understanding please check the jpeg attachments "bootloader unlock step 3" and "bootloader unlock step 4" below.

Now Power off your Sony Xperia Z3 tablet compact and then press "volume up".

Connect the tablet to PC.

To proceed further you will need adb. Click here to download adb.

Install the adb setup on your PC.

Go to the folder C:\Program Files (x86)\Minimal ADB and Fastboot

Press "shift" button and right click in the empty space inside that folder.

You will get the option "Open Command Window here"

Select that option.

Now type the below commands (these commands are there in the bootloader unlock step 3.jpeg and bootloader unlock step 4.jpeg" below in attachments)

fastboot devices

fastboot i 0x0fce oem unlock <your unlock code>

Thats it. Your bootloader should be unlocked now.

Reboot the device and go inside the Settings -> Developer settings -> Check USB debugging and unknown sources.

3) Installation of TWRP and Root.

You need .img file for this.

From this thread I downloaded the .img

File name will be Z3TC-stock-twrp.img.

Just rename this file as boot.img and place it in C:\Program Files (x86)\Minimal ADB and Fastboot

Power off your Sony Xperia Z3 tablet compact and then press "volume up".

Connect your tablet to PC.

Go to the folder C:\Program Files (x86)\Minimal ADB and Fastboot

Press "shift" button and right click in the empty space inside that folder.

You will get the option "Open Command Window here"

Type the below commands one after the other.

fastboot devices

fastboot flash boot boot.img

it should say "finished". check the "successful bootimg commands.jpeg " in below attachments.

Reboot the device.

Download the Pre-rooted flashable Zip from here

Download the SuperSu from here

Copy the Prerooted flashable zip and SuperSU to your SD card.

Switch off the Tablet.

Go to recovery by pressing "power" & volume up and down alternatively.

You will now enter TWRP.

Install the SuperSU zip file.

Then Install the Pre-rooted flashable zip file.

Reboot and you are done!

You will now have working Root, TWRP and awesome Lollipop firmware on your beautiful Sony Xperia Z3 Tablet Compact.

4) Final step Backup TA keys.

After rebooting the device.

Once it enters the homescreen.

Go inside the Settings -> Developer settings -> Check USB debugging and unknown sources.

Connect the Tablet to PC

Download the backup TA software from here

Extract it on your PC.

Double click on the Backtup-TA.bat

It will identify your device.

Just back up your DRM keys from the options on your screen.

I read online and in some threads in XDA that backup TA software needs the device to be rooted and that is why I kept this step in the end.

I completely agree if you guys find the above procedure tedious.

After going through many threads and websites this is how the steps panned out.

This is the procedure that worked for me in the end.

I did have few hiccups and bootloop as well. Then I just kept it flashmode and re-flashed the lollipop ftf file using flashtool with "wipe data" option checked.

That solved the problem.

Coming from Samsung devices I had to find out what was fastboot mode, flash mode, how to enter recovery and how to use flashtool. It was all new to me.

But I didn't give up and went through the grind.

Result? Super Sony Xperia Z3 Compact SGP 621 with Root on Lollipop firmware with Excellent battery life.

Thanks to all the brilliant developers on this site who in various threads explained various aspects of rooting. It is because of them I was able to put everything together.

Please find all the screenshots in the attachments below.

Hope you find this information useful.

Thank you

Cheers!