I just launched the Amazon Prime channel after PKinVA's post, and it's totally different looking, meaning the channel had a major update, so it may be glitchy for a bit till Amazon resolves all the glitches. I repeated the steps users had and didn't experience the crash, so my Roku Ultra device doesn't seem to be affected currently. I'm unsure if this will help you PKinVA, but it may be a cache problem with the new update conflicting with the old channel version on your TV. However, if it's on Amazon's end, there is little you can do until they resolve it, but there are temporary workarounds that you can do. These workarounds aren't very pretty, but at least you can watch that channel's content until this issue is resolved. Usually, these types of glitches are device-specific, meaning that even though the Prime video channel is not working on your TV right now, it's working on other streaming devices, including Roku devices.
So try this instead of the above steps:
1) Remove the channel (same as above)
2) Clear the cache -- this won't hard reset the Roku and won't clear your passwords.
On the remote: Press the Home button 5 times, Up button 1 time, Rewind button "<<" 2 times, and Fast-forward button ">>" 2 times.
The Roku will flip the menu up three times, freeze and then restart.
3) Add the channel (same as above)
You can also try manually updating the Roku, which will only work if Amazon has rolled out a patch.
Try using Amazon, and if that doesn't work, repeat these same steps but log out of your account first:
Tap the left arrow to get to the menu, scroll down to settings, and scroll down to sign out. Then repeat the above steps. Then log in and hope for the best.
Hopefully, this fixes the problem once you sign back in. If it doesn't, then Amazon needs to fix the problem on their end. If this issue continues, since this might be specific to your Roku TV, you need to contact Amazon and let them know you can't access Prime video.
Now here are the non-pretty workarounds if the above steps didn't work, and you probably won't like them, but it will get you watching Amazon again asap: If you have a Roku device, for the time being, you can try to connect that device to your TV and see if you can watch Amazon on that until this issue is resolved with your TV.
Another one of my very non-pretty suggestions (which Roku probably won't like) is to have a redundant backup streaming device to attach to your TV (that's not a Roku), so when channel glitches occur after major updates, you can temporarily switch to that other device, so you can continue watching the channel's contents until it's resolved on your Roku TV. It's not the best solution to have to attach a Roku or a non-Roku streaming device to a Roku TV, told you it wasn't pretty, and it can be expensive to have to buy yet another TV streaming device, but it's helpful in a pinch when a channel is glitching on one device, and you want to watch something on that channel now instead of waiting for the glitch to be resolved, which usually doesn't take all that long, but it's super annoying having to wait, I know.
I'm not implying switching to a different device permanently because all devices glitch at times, but just to have another device when this happens. Once the channel provider fixes the issue, you can then switch back. It is very unlikely that two different devices will have a channel glitch at the same time. For the time being, if Amazon keeps crashing and you don't have another streaming device, if you have a PC, you can attach that to the TV and watch your movie/show that way until this is resolved on Amazon's end. Or, if you have a tablet, you can mirror the screen to the TV. Again not a pretty workaround, but it's something you can do until Amazon resolves this.
I know these non-pretty workarounds aren't what you want to hear if the above steps didn't work, but at least you can do a temporary workaround so you can at least watch your movies/shows now. And once Amazon fixes this, you can then watch Amazon directly on your TV again, and soon you will be able to; you just have to be patient till it's patched.