[Sony Xperia XZ Premium Questions & Answers] lonewolfbtown:
First if your phone blows up, freezes, dies or boot loops it is not my fault. I will help if i can but if you blame me. I will not feel bad

First things first Here's what you need!!!

-flashtool- If you can find the xperia ftf downloader only more power to you. http://www.flashtool.net/index.php

-newflasher, This is the correct tool for flashing new firmware on the xz premium https://xdaforums.com/crossdevice-dev/sony/progress-newflasher-xperia-command-line-t3619426

-twrp image: https://dl.twrp.me/maple/

-root aka magisk https://xdaforums.com/apps/magisk/official-magisk-v7-universal-systemless-t3473445

-minimal adb. Not gonna link it. so easy to search. INSTALL THIS BEFORE EVERYTHING ELSE

Ok here we go to getting to 9.0 and root:

Getting your firmware

-First install flashtool after you download it.

-Once its installed you want to navigate your explorer to where it was installed, and find the drivers folder. Click the drivers exe and it will come up with many options. You want adb and fastboot. I think its the first two. Click install

-Drivers installed? OK moving on! Open flashtool and navigate to xperifirm. Should be on the toolbar. Another window will pop up with a bunch of xperia phones and years. Find your phone. click your region. In the right screen of the window it will show what firmware is available. Most recent pie version will end in .24. If unsure, GOOGLE THE FIRMWARE NUMBER.

-CLICK ON THAT FIRMWARE AND IT WILL BEGIN TO DOWNLOAD. after download it will unpack it

-Once it unpacks and finishes, close the download window. Close xperifirm. Dont touch flash tool. Leave THAT OPEN. Flashtool will then unpack the ftf (which is important that it does) and the bottom bar will have progress bar. It will be clear when it finishes or fails but you will see red letters if it did.

-Firmware unpacked? Great! Extract your newflash firmware. All items in the zip must go into the folder where your firmware was downloaded. Mine looks like this C:\Users\rocke\.flashTool. It will be in the download folder and it will have your unpacked firmware. Go into that folder and it will have a bunch of files from your ftf. Move your new flasher files in there. Make sure boot folder is emptied into the main folder where are the others are and new flasher. Delete boot folder.

Flashing time

-hold volume down and plug in phone to pc. Green light should come one.

-Open Newflasher.exe

-a few questions will appear. I dont type (y) = yes on both questions cause its kinda pointless unless you need gordon gate drivers and u want to back up something that i think i dont need/

-WHoooooosh! Command lines will start popping up and your phone is being flashed. Let its do its thing

-Eventually it will tell you you can disconnect your phone after u close the window. Boom android 9

Give me the root captain!!!

root.....a dangerous but such a fun little thing

-first your twrp. Hold volume up and plug in phone. Blue Light will come on. the twrp image must go in the minimal adb folder. Other wise adb will think your crazy and say it doesnt exist.

-type this in minimal adb fastboot devices. it will show if a fastboot device is available. If not we have problem with drivers. If yes. Then we keep trucking on

-flash twrp. type this command in fastboot flash recovery twrp.img (rename image obviously) It will flash it to the phone.

-Reboot phone into recovery. Volume down and power button. Release at sony logo or it might be the unlocked bootloader warning. Cant remember. Either way release power button on that logo and keep holding volume down.

Boom your in twrp.

-if magisk wont move over to your sd card in twrp. its time to adb push

-adb push magisk.zip /sdcard

it will move the file.

-Find where you pushed it and install magisk. It will do its thing.

If you followed the instructions your phone should be rooted and you want need a drm fix to cover the holes of the BL unlock. If hit any snags message me or reply here