Yay! This works. Everything I needed was in the forum, but I have a bad habit of trying to complicate simple things, so I'll run through my process and some pitfalls.
My machine: Windows 10 64-bit.
Edit: These are my steps for flashing the NVR, not the cameras.
Step 1: Make USB-serial cable using the color scheme above. (RedMolex-BlackUSB | BlackMolex-WhiteUSB | YellowMolex-GreenUSB)
Step 2: Plug USB into computer. My computer recognized "Prolific USB Serial" something with error in device manager. I also got a warning about a USB device trying to draw too much power. I did a google search for "Prolific Serial Fix Windows 10" and found a driver that worked. Unplug USB, Install driver, Plug USB during installation, restart
Step 3: Serial port USB should now be working. NO MORE yellow exclamation icon on the USB serial prolific device thing. USB-serial adapter should be plugged into the small 4pin port on the motherboard of the NVR.
Step 4: Open Putty using the serial configuration mentioned in this post. Mine was on COM4, but apparently this can be different and should show up in device manager.
Step 5: At this point you should have a Putty terminal over Serial connection. If you power on the NVR you should see activity in the terminal (Putty). THIS IS SIMPLY A DISPLAY AND WILL NOT TRANSFER DATA EVEN IF YOU USE CORRECT IP ADDRESSES.
Step 6: Screw everything up. This step is optional. At first I connected an ethernet cable from my laptop to my NVR. I had no idea what the ip address of the NVR was so I booted up a few times and looked for the IP address. I saw something and tried that several times with some promising looking text. Turns out the IP I was using was the host IP for the NVR that all of the cameras are connected through. I tried a manual address on the laptop with random guesses for the NVR. None of this worked. Time to think instead of just doing stupid crap.
Step 6.5: Fail more. Again this step is optional. I looked all over my house for a spare router, switch, etc. to get my laptop and NVR on a separate network from my home. No dice. I gave up and put my NVR on my home network and connected to my home network on my laptop via wireless.
Step 7. Fail + revelation. Now I know my laptop and NVR IP addresses are correct. I still can't get the thing to update. From the terminal, I can interrupt boot with ctrl-U, I can input IP addresses. It says Downloading...T T T T T T T....etc. T stands for "timeout" as far as I can tell and at this point you need to just turn the NVR off and figure something else out.
Step 8. Realize that Putty is just providing a terminal, a monitor, a display. The putty session is not hosting any files even though I put the digicap.cav file in the folder. This is where you need to have a
TFTP server running ALONG WITH your putty shell. (ooohhhh......)
Step 9. Start TFTP server. I used the hikvision one that is able to be downloaded from mirrors. I couldn't find it on the hikvision site, but downloaded it elsewhere. Just put the digicap.dav file in the same location as the tftpserv.exe file.
Step 10. Go back to putty shell, power on NVR, press ctrl-U. Put in correct IP addresses, press "y" to confirm, hopefully that worked.
There are probably a few steps missing here. Feel free to keep this thread going with questions.
