[Shield Q&A] gogul1:
Root explanation

Hi here is the main walkthrough from github but as I said there are a few plot holes for people who are new.

If your SHIELD is already unlocked, you can skip this section.

SHIELD ships with an unlockable bootloader. The bootloader is locked by default, which prevents anyone (including yourself) from booting custom OSes and changing system partitions to potentially obtain extra privileges. This is a significant security feature: in the event that your device gets stolen, an attacker will not be able to retrieve your personal data or use your device if your lock screen has a password set.

By unlocking the bootloader, you allow anyone with physical access to your SHIELD to boot custom images and flash system partitions. This opens the way for an attacker to access your personal information or physically damage your device. For this reason, unlocking the bootloader will erase all your personal data like a factory reset does (so a potential thief cannot get it) and will also void your warranty.

If you know you really, really want to take these risks, here is how you unlock SHIELD's bootloader.

Switch your SHIELD off (long press the NVIDIA logo button and select Power off).

Power your SHIELD on while maintaining the back and home buttons pressed (these are the two buttons that lie under the big NVIDIA-logo button, on its left and right). Release them once you see the bootloader screen.

Connect your SHIELD to your computer using a USB cable.

On your computer, enter the following command:

fastboot oem unlock

This will display the unlock menu. Read the disclaimer and think one last time about what you are doing. This is your last chance to stop.

Use the back and home buttons to select your option. If you decide to continue, select Unlock and press the NVIDIA-logo button to validate. Your personal data will be erased and your device marked as warranty-void permanently.

Regardless of your choice, you will be back to the bootloader screen. Using the same buttons, navigate to Poweroff and select this to power your SHIELD off.

Rooting SHIELD

Now your bootloader is unlocked, but you still don't have root access. For this, we need to install SuperSU, and we will do so by booting a custom Linux image that will do this for us.

Power your SHIELD on while maintaining the back and home buttons pressed (these are the two buttons that lie under the big NVIDIA-logo button, on its left and right). Release them once you see the bootloader screen.

Connect your SHIELD to your computer using a USB cable

On your computer, navigate into the directory containing this file and enter the following command:

fastboot boot zImage_dtb ramfs.img.gz

The kernel and ramdisk will be downloaded and started. You will see 4 penguins on your screen, and the message ROOTING SHIELD will appear. Shortly after, your device will reboot. Congratulations, you are rooted!

For some unknown reason USB debugging in Developer options might become unchecked after rooting. You will need to re-check it if you want to use ADB.

It is safe to perform the rooting operation as many times as you want (e.g. after an OTA). Your user data will not be erased by rooting itself, it is the act of unlocking the bootloader that does.

Is there anyone who can add a little to this to make it more simple for a noob like me?

I understand there is a file set that is at the top of the page and I downloaded the files which include zImage_dtb ramfs.img.gz

but don't know how to utilise them etc

There are no videos on youtube of how to do it and if anyone can add just a few more steps so that I know where I'm going with this (don't want to brick my system).

I just want controller support installed like Tincore or gamekeyboard so I can unlock the potential of the games library on GooglePlay.

Thanks for reading.