Killing OTA updates on 55U8N and 55U8K firmwares:

Yes, if you don't do this or take your TV offline, your TV will always go to an unskipable update prompt.  Cool, right?

This is a pretty advanced guide requiring some command line PC usage.  If this bothers you, just take your TV offline and forget about this.  No shame.  That works!

1.) Step one, you need to flash the firmware to your TV and set it up as a basic TV.  Do NOT give it network access under any circumstances, we can do all that later.

2.) 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).

3.) 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.

4.) Now, you'll need a 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.

7.) Connect your TV to your network.  Note its IPv4 address when you do so.

8.) At the PC, type the following commands substituting your TVs IP address for the one I provide as an example (you can find it in network settings): 

adb connect 192.168.1.4:5555
adb shell

9.) You are now in an adb shell on your TV.  Don't worry if the unskippable upgrade prompt has come up now, we have what we need and we will kill it shortly.

10.) Type the following command in your TVs shell:

pm disable-user --user 0 com.vt.tv.ota

11.) type "exit" (without quotes) to exit.  Again to exit the cmd, ya noob.

12.) The upgrade app is now disabled and should bother you no more.  I like to reboot the TV for good measure here to be sure, but honestly, it's probably fine just to leave it.

13.) You are done.  Go play with your TV.