I assisted a family member in getting RT updates working again. The clock was lagging by a month -- despite time sync settings set to time.windows.com -- but anyway, after bringing it a month forward in time, two small sized (30ish MB) important updates and the optional January 2018 Preview updates for 8.1 RT appeared. I opted to apply them. This resulted in a successful startup, but blank login screen, except for a flashing pointer and flashing wifi icon. I found an x86-related article on Lenovo forums (topic: Y500 windows8.1 black screen blinking cursor/wifi) which describes the same behavior. I was left with no choice but to Refresh after intentionally triggering Automatic Repair. Thus, I have no historical data on the actual cause as far as I can tell from the event logs. All I know is that after I applied the last round of important updates, which did not require a reboot, I then applied the optional January previews, and that required a reboot. Following that reboot, I ran in to the blank screen issue. Are there any blogs or information sources detailing this behavior?