You need to boot into Linux on a computer with the SD card inserted into the computer you're booting from. The best way to do this is to download a distro that you can burn to a DVD. You then boot from the DVD when you restart your computer. I used kubuntu-19.04-desktop-amd64.iso.
Next, after you boot from the DVD, make sure your internet works (you will have to connect your WiFi in the Kubuntu desktop) and then you need to download the Armbian package that contains the DTB that corresponds to the kernel you updated to. In my case it was Kernel 4.19.38.
Open Firefox in Kubuntu, and navigate to https://apt.armbian.com/pool/main/l/
This is a list of directories. The directories you're interested in are the ones that are formatted as such: "linux"-(version)-"platform"
In my case, I needed to navigate into the "linux-4.19.38-sunxi" directory.
If you don't know or remember the kernel version you installed before your device was bricked, then look at the dates of the directories. In my case, I installed the latest kernel two or so days ago, and the date listed for 4.19.38 is 03-May-2019. The latest version isn't necessarily the newest version. Later beta versions can have a newer version number but an earlier date. I'm not sure how important this step is, but it's worth mentioning nevertheless. Make sure you also get the 32-bit version if your Linux install is 32-bit. In my case, the NanoPi Neo is strictly a 32-bit device, so there was no room for error there.
Next you need to download the correct .deb package from within the directory, in my case it was "linux-dtb-next-sunxi_5.83_armhf.deb". Firefox will by default save the file in "/Home/Downloads". For the purpost of this post, we'll use this directory as a reference. After the file finishes downloading, you can click 'Open Containing Folder' and it will open the directory. Now right-click on 'linux-dtb-next-sunxi_5.85_armhf.deb' and click 'extract here'. It will create a directry called 'linux-dtb-next-sunxi_5.85_armhf, open that directory. Right click on 'data.tar.xz' and click 'extract here'.
Next, you need to move this directory into the SD card, but depending on how you have the SD card connected to the computer, you may need root access. You should be able to do this without root if you have it connected to the computer through a SD to USB adapter. We'll be focusing on a scenario where root access is required.
You now need to open a terminal in Kubuntu. Click on the 6 dots at the bottom left corner of the screen, this opens up a screen of programs. On the right side, click on the second dot, this will display a second page of programs. You should see a program called 'Terminal'.
Click it, and this will open a terminal window. Type 'sudo passwd root'. Enter a password, and then again to confirm it. Next, type 'sudo -i'. You should now have root access. Now you need to move one of the subdirectories from the directory of the archive you extracted earlier to the boot directory of your SD card. First, you will need to go into the 'boot' directory of your Armbian Distro in your SD card. Don't confuse the 'boot' directory of the Kubuntu root directory for the one in your SD card.
To access the boot directory in your SD card type the following:
Now you should see a long string of numbers and letters, enter that directory. In my case, I need to enter:
Now we need to move a directory from the archive you extracted earlier into the boot directory and then we need to create a symlink. Type the following:
mv ~/Downloads/linux-dtb-next-sunxi_5.85_armhf/data/boot/dtb-4.19.38-sunxi . (<-- the period after the space is important!)
ln -s dtb-4.19.38-sunxi dtb
Next type 'ls -l'
If you've done things correctly, you should see this entry in the resulting output:
lrwxrwxrwx 1 root root 18 May 7 15:21 dtb -> dtb-4.19.38-sunxi/
To confirm, type 'cd dtb', then 'ls'. You should see a bunch of files.
If you do, type 'shutdown now'.
Put your SD card back into your device and boot it. If you did things properly and it now boots, SSH into it and run 'apt-get install linux-dtb-next-sunxi'
That installs some other stuff into the dtb directory that uboot complains about during boot. Not sure what they do, but it's probably a good thing to have.