I GOT MINE WORKING!
Here is what I did:
I went to this link:
https://developers.google.com/android/nexus/images?hl=vi and downloaded the 4.3 (Jelly Bean) factory image for my device. In my case, since I have a Nexus 10, it was this file: 4.3 (JWR66Y)
https://dl.google.com/dl/android/aosp/mantaray-jwr66y-factory-3d8252dd.tgz
Then inside that file was "image-mantaray-jwr66y.zip". I extracted that file. I then took the files I extracted (boot.img, recovery.img, system.img, userdata.img, and cache.img) and moved them to the "Nexus10RootNew" folder that I had previously downloaded from here:
http://downloadandroidrom.com/file/Nexus10/Nexus10RootNew.zip#
Then Open file manager
Navigate to the folder you extracted the files to (Nexus10RootNew)
on the left pane select the folder, press SHIFT and Right Click mouse, then select "Open command window here"
From the command window, run >fastboot reboot-bootloader
It should reboot to the bootloader.
Then, run the following commands (note the .img files below are from the 4.3 image file, not 4.4):
fastboot flash boot boot.img
fastboot flash recovery recovery.img
fastboot erase system
fastboot flash system system.img
At this point you have a clean install of 4.3 JSS15R.
Then I removed the 4.3 .img files (boot.img, recovery.img, system.img, userdata.img, and cache.img) that I just used from the Nexus10RootNew folder and moved the 4.4 (KRT16S) recovery.img file into the Nexus10RootNew folder.
Then, when back in bootloader, go back to the command window and type:
>fastboot flash recovery recovery.img
Note this is the 4.4 (KRT16S) recovery.img file now.
(^^^^^Looking back, I don't think this is necessary and may be why I have some weird issues popping up)
After it's done:
>fastboot reboot-bootloader again and go to recovery using the volume buttons
select and enter recovery mode
wait for dead droid to appear
press both Volume UP and Power at same time and you should get the load menu
select "apply updated from adb" and press power after selecting
orange colored type will now appear at the bottom of the screen
on your PC
>adb sideload ota.zip
Make sure this is the 4.4 (KRT16S) OTA file from here:
http://android.clients.google.com/p...gned-mantaray-KRT16O-from-JWR66Y.279e5e23.zip
wait till you see its completed successfully
then reboot
It should now load Kit Kat (it takes a while) and then start optimizing apps. At that point you know it's successful. Just wait for it to finish optimizing the apps and enjoy!
I ended up with KRT16O somehow, not sure since I used the KRT16S files but I assume it will notify me of the KRT16S OTA being available at some point. I have not attempted to regain root or anything yet. I'll wait for the next OTA before making it "unstock" to try to avoid any problems this time.
Note: I did end up losing all my homescreens so I'll have to move all the apps/widgets back into position but the apps and the app data is there. I did have to update a few settings like turning WiFi back on and such.