I'm assuming your remote and other channels work fine, just not the Amazon Prime Video.
I'm also assuming that your acct under Settings>System>About & click again to the right shows the MicroSD Card and % used. If so then it is formatted and installed properly.
This should be an easy fix - if a channel app stops working simply uninstall it and re-install it. The Roku Gremlins corrupt channel apps now and then. You can find the channel under "Search" and type Amazon Prime or just Prime Video. Select uninstall and then when that's done select install. It ought to work fine after that. I have had channels stop working before and had to do this uninstall-reinstall step before and it always works as long as the channel app is still available & Prime Video is still available.
The 4230 is still a respectable player, spec-wise. It is approaching 6 years old (released Apr 2015), and it's possible that it's developed a fault.
Don't forget the critical step of rebooting the Roku AFTER removing a channel and BEFORE adding it back. If the reboot doesn't happen, it wasn't really removed. Either pull the power for 30 seconds or use the Settings/System/System restart menu. DO NOT use the System Reset menu. That wipes your Roku to factory delivered condition and you have to set everything back up again.
I have my initial problem solved as I posted, and the Roku unit & remote are working fine now. As far as my future with Roku, my standard HD TV is 7 years old now and I will be replacing it with a 2021 model year Smart TV when they come out in the spring and be done with Roku forever. Roku is currently having a spat with Spectrum and the carrier fees for their streaming app which I use, and are threatening to cut it off. So that was the beginning of the end of Roku for me.
Hey, this worked great on my Roku 3! Thanks, man!
Odd thing is, my SD card had been working fine for over a year before it decided to flake out on me. Very odd. BTW, if anyone is interested, I asked Roku about which card to buy after some less satisfactory results with a different SD card, and they had this to say:
"We understand your concern regarding the micro SD card issue on the Roku. Roku will support the micro SD card with class 2-8 and with the memory 2 GB-32 GB. That is why you are unable to use the micro SD card on the Roku. Kindly try with the micro SD card with above class types and reply to this email if it is not working."
Hope this helps someone!
same one I have - and when I insert the micro sd card I bought from Roku, the remote will not operate to allow me to select format. Have you found a solution>
Go to this post and scroll down to the eighth comment which is my solution that I found works.
I posted the solution it on my original post but cannot find it.
Here's the solution that I wrote about previously:
Ok, here's how I solved this with the micro SD card installed & formatted and the remote working fine with the SD card installed.
1) With everything OFF, install micro SD card contacts up. Then turn on TV & Roku devices.
2) Screen will show prompt to Format the SD card but remote will not work. Remove battery cover on remote, point towards Roku unit and press and hold the "pairing button" until the light next to the button flashes (if the remote has a light), otherwise hold pairing button for about 5 seconds. Then the remote will take about 20-30 seconds to finish "pairing" back up with your Roku unit. The screen will tell you when the "pairing" is complete.
3) The remote will now work but the SD card is still not Formatted yet. Turn off/unplug the Roku from power and wait 10 seconds and turn back on. The prompt to Format the micro SD card should appear and the remote will work to select "Format". If the remote doesn't work yet, re-pair the remote and start the Roku reboot process again.
You can verify that the micro SD card is installed and formatted by clicking on Settings>System>About>click to the right until you see your Roku account and at the bottom it will say Micro SD card and a % used and total memory used of the card total. Mine says 7% used (o.1/1.9 GB) for a 2 GB micro SD card.
Now, why in the heck can't Roku give us instructions like that???
Apparently the hardware configuration is changed enough by adding a micro SD card that the remote needs to be re-paired back to your Roku unit.