Hisense 55/65/75" U8N / U8K firmware root database and guide.

First off, this guide WILL wipe your TV so bear that in mind.

This is a guide to rooting the TV with Magisk.  To date I have personally made boot images for all the relevant firmwares of this set that could be wanted or needed (to my knowledge anyways).  To root, first you will need the following supplies:

1.) A single USB-A to USB-A male to male cable, like this.  You will be connecting this from the back USB port (the black one) on the TV to your PC.

2.)  Some technical knowledge.

3.) Yourself, and a Hisense 55/65/75" U8N/K model GoogleTV televison.

4.) a rooted boot.img image from the following table (not the stock one, that is for unrooting):

Firmware Version / Download Link	Stock boot.img Image	Rooted boot.img Image
55U8K_55U8N_55E85GUA_N0918.zip	N0918_stock_boot.img	N0918_rooted_boot.img
55U8K_55U8N_55E85GUA_O0223.zip	O0223_stock_boot.img	O0223_rooted_boot.img
55U8K_55U8N_55E85GUA_O0730.zip	O0730_stock_boot.img	O0730_rooted_boot.img
55U8K_55U8N_55E85GUA_O1030.zip	O1030_stock_boot.img	O1030_rooted_boot.img
55U8K_55U8N_55E85GUA_P0414.zip	P0414_stock_boot.img	P0414_rooted_boot.img
55U8K_55U8N_55E85GUA_P0828.zip	P0828_stock_boot.img	P0828_rooted_boot.img

Now with that in hand, first step is to enable ADB debugging and enter an adb shell, follow these steps to get there:

1.) Now, enable developer tools on your TV.  You do this by going to System -> About -> Android TV OS Build and clicking OK on it until it makes you a developer (should take about 5 times and count down as you do it).

2.) Now, go to the developer options menu.  It should be in the main menu "System" page.  While there, turn on "USB Debugging" and don't touch anything else.  There is bad stuff you don't want in there.

3.) Reboot your TV once.  You can't get a USB adb connection without this (it's best for this guide).

4.) Now, you'll need a PC.  Connect one end of the USB-A cable you bought into back black USB port on the TV, and the other to any on your PC.  On that PC download ADB tools for Windows (assuming it's a windows PC) here:  https://dl.google.com/android/repository/platform-tools-latest-windows.zip

5.) Unzip that to a directory of your choice, and open a cmd prompt and cd to that directory.

6.) Please read the following steps carefully before executing them.  Type the following command without quotes:  "adb shell"

9.) You are now in an adb shell on your TV.  Now type "reboot bootloader"

10.) Your TV should reboot and go completely dark.  That's ok, it's still alive and we'll wake it up soon.  type the following commands in order (and no the second "fastboot" is not a mistake):

fastboot unlock flashing
fastboot reboot fastboot

11.) Now your TV should come up with a scary looking screen, you are almost there!  Copy the boot.img you downloaded above to the same directory you unzipped the platform tools into, and type the following:

fastboot flash boot_a boot.img
fastboot flash boot_b boot.img

Where "boot.img" is the name of the boot.img you downloaded.

12.) Reboot, watch your data erase, and enjoy root and all it's upsides and downsides!  To unroot, simply follow this guide again, but use a stock boot.img from the table above for your same firmware.  At the end be sure and reboot to the bootloader again as in steps 9-10 but instead of "fastboot unlock flashing" do a "fastboot lock flashing" to relock the bootloader.  Otherwise, enjoy!