So this morning, I went to the support link for Samsung. You'll find it listed on the www.amazon.com/help/samsungupdate page. I live chatted with a support person from Samsung and they had me change the DNS settings, as others have mentioned above. It worked for me. However, I had ALREADY done the complete firmware update last night (updated to 002003) so if you haven't done the firmware update yet, this may not work for you ( you might want to try either way). Try this:
1. Set the Source to TV (rather than HDMI)
2. Go to Menu
3. Choose Network
4. choose Network Status
5. choose (Select) IP Settings
6. Scroll down to DNS Setting and hit button until you can change it to : Enter Manually
7. Scroll down to DNS Server. Then choose each number to be: 8.8.4.4.
8. Scroll down and hit OK
9. Get out of that Menu
10. change Source back to HDMI, instead of TV
11. try opening Smart TV Amazon app
12. If it asks you to update just the Amazon app, go ahead and do that.
Hopefully, this should work. It worked for me.