I experienced the same issue trying to update my Roku Express (3900 series) over the weekend, except it appears the problem occurred after the update had already started. I was stuck on the update screen, with the only two options being to "Cancel" or "Try again." I eventually had to manually reset my device by locating the reset button and holding it down. I realize that not all devices may have a reset button, but in this case this worked for me as I was finally able to update the device, although at the cost of resetting all the channels, etc. Hope this helps
