I solved a problem with a Roku 3 update this past weekend. The Roku box was a freebie from my internet provider when I signed-up for their streaming service package. The initial setup worked fine, but after a few weeks the system froze. I had to power cycle the unit to get it back online. After a second-time freezing I checked manually for system updates. At this point the online prompts told me there was an update available to version 7 of the Roku OS. It looked like the update successfully applied. However after a reboot, the system went back to version 5.6.
The solution I found was to do a factory reset of the device. During the reset the system automatically updated to version 7 of the Roku system software. I did have to re-authenticate with my Roku apps, but that was much better than the system freezing and I’m happy the Roku device isn’t defective.