I'm not sure if you read my prior update....
I was able to successfully regain use by pressing the physical reset button 20 times as soon as the Roku letters starting bouncing. Literally pressing the button 20 times - once a second. To ensure greater chances of success unplug all cables and allow the power block and 4640x to fully cool down. Say 30 minutes or so. Mine had been unplugged and disconnected - I had pulled out an old Blu-ray player in order to stream.
If you're using a Wi-Fi connection and it fails, try repeating the process with an Ethernet connection. I know it's difficult and a hassle to move a TV close enough to connect an Ethernet cable from your router to your 4640X and an HDMI cable to your TV.
If pressing the reset button 20 times while connected via Ethernet is successfully, you will be prompted to set up your 4640X as if it were new. Go through the process of setting up the 4640X while connected via Ethernet. Delete as many unused, junk, or underused apps as possible in order to free up device memory. Then open each app and login. Keep in mind deleting apps on your 4640X will remove them from all other Roku devices. Apps are stored locally on each device. However changes are linked to your Roku account, therefore on all devices. Downloading a new app on one device will added the app thumbnail on all other Roku devices. However the app will not download to the other devices until you open that app on each device. Meaning the app thumbnail will be displayed but not taking up memory on the device until you open it. Hopefully that makes sense.
For those using an optical cable. Do not plug in the cable until you've successfully regained use. While the optical cable should not affect the player, it's worth a try. Nothing about this Recovery Boot loops makes sense. Some recover with holding the reset button for 20 second. Others recover after pressing the reset button ten consecutive times. I had success pressing it 20 consecutive times over 20 seconds.
Due to the fact many of us were able to recover with different methods, I urge each of you to try different methods. Methods include via Wi-Fi and Ethernet - connected directly to a router and/or a Wi-Fi repeater, with-w/out optical cable, pressing and holding the reset button for 20 seconds, pressing reset 10 times, pressing the reset 20 times, using a different HDMI cable, and trying on a different TV. If your Wi-Fi is weak (DSL or due to a lot of connected devices) take as many devices offline as possible to improve your 4640X chances of getting through the entire setup process. The setup process includes updating its software and downloading apps. If the Internet connection is weak or slow there is a risk the update and/or apps could fail to download completely or at all. Meaning you could trigger the 4640X going back into Recovery Mode. After you've setup your player - deleted apps and opened and logged in remaining apps, reboot (not reset) the player. If all is well switch the player Internet connection to Wi-Fi. Once connected via WiFi disconnect the Ethernet cable. Open and app to test streaming. If successful you may resume normal operation. If there are any issues you will need to press the reset button once in order to try to clear the issue.
Once users recover I recommend using a Micro SD to ensure there is sufficient memory on the 4640X for future updates. While Roku can't or won't tell us what caused some 4640X player to fail, it is my theory those of us affected either didn't have enough memory for the update to completely install. Or our Internet connection was somehow compromised or interrupted during downloading of the update. Expanding the memory via Micro SD may prevent this from happening during future updates. Finding a way to improve internet connectivity (moving the router or player, using an Ethernet connection, or adding a Wi-Fi repeater) is another step towards possibly preventing the same issue from occuring. Again.... these are steps I took based on my theory, not fact.
Cheers!
