Below are some instructions for updating firmware on a US model 4500 (whether an AFXZA or a BFXZA). I would assume that the 43" and 51" use the same firmware. I'll be using the 43" in my instructions. It seems as though if you have version 1003, even if you have a BFXZA, all that seems to mean is that the TV was made in 2013, but released in 2014.
1. Go to http://www.samsung.com
2. In the search field, type PN43F4500 .
3. Whether you have an AFXZA or a BFXZA, under PN43F4500AFXZA, click on Support (US models only).
4. Click See All Downloads.
5. Under firmware version 1027.2, click Zip.
6. Click Send.
7. Click Save.
8. So we can all troubleshoot at the forum, we should save the T-NVTF6AKUC file to our desktops. So select the Desktop as the target location.
9. Click Save.
10. Wait for the download to finish. If you see some kind of download completed notification message, close it.
11. Unzip T-NVTF6AKUC to the desktop. Let it save the extracted files to the default location. Be sure to uncheck "Show extracted files."
12. To avoid confusion, delete T-NVTF6AKUC.ZIP, and not the new folder called T-NVTF6AKUC.
13. Back up all important files from the USB stick you plan on using.
14. Format your USB stick. I'm not sure whether FAT16, FAT32, or NTFS will make a difference.
15. Copy the T-NVTF6AKUC folder to your USB stick. The TV will look for this folder with the two files in it.
16. Plug your USB stick into the TV.
17. Have your TV look for the update.
A. If your TV doesn't find the update, then we'll have to chat with Samsung about this.
B. If your TV does find the update, hit ENTER/OK on your remote. The TV will start updating. Do not touch the TV until it reboots and the update is finished.
19. Disconnect your USB stick from your TV.
20. In order to avoid any conflicts from the previous firmware version, reset all your TV's settings to the factory defaults.
21. Make all your settings. Because new firmware has corrected some HDMI picture issues, you might wind up with picture settings other than the ones you made before you updated your firmware. The settings I posted were made with 1027.2 installed. Speaking of which, I have another revision I never posted here yet.
I only did the update once, so I forget exactly what menus, submenus, subsubmenus, etc. you have to get to to launch the update procedure, but it sounds like you guys know that part well enough you can do it in your sleep. I think the harder part is preparing your computers and USB sticks so your TVs can recognize the update.