Experiences with CF-SX2 and CF-W8.
1. I bought the SX2 less than a year before Windows 10 was released. By that time, Panasonic had already abandoned support for the model. No new drivers or bios, no support for Win 10 upgrade. I took a chance a couple of months ago anyway. The upgrade was easy and flawless. Kudos to Microsoft, none to Panasonic.
2. My older Toughbook is a CF-W8. It was running Windows 7, using a driver package provided by Panasonic. I put off until yesterday upgrading to Win 10: Ain't broke, why fix? I hadn't been using the machine, so I figured that I might as well try the upgrade. No loss if it didn't work, particularly if I could restore Win 7 for 30 days.
It was slow, but the install seemed to go as well as for the SX2. I added a user, encrypted some files, did some tweaking. What I did not do was set a system restore point when all was running. That came back to haunt me when I thought rolling back might be a solution.
Ok, all working. Then since I hadn't been using the machine, I was curious about the battery. I ran the Panasonic battery recalibration utility overnight. In the morning, I rebooted and clicked on the battery icon in the taskbar. There was a square with a sun symbol and 100%. I wasn't sure what it meant, but I clicked on it. Screen went black and stayed black.
From that point on, all I could do was force shutdown and reboot each time into a black screen. That was before the Lock Screen appeared. I was only able to boot Safe Mode with Networking. I downloaded and ran Driver Talent. It said all my drivers were good. Tried to reboot in log mode - black screen.
Basically, the only way I could do anything was to boot Safe Mode with Networking. From there, I thought I might just revert to Win 7. From MS: Settings > Update & security > Recovery and select Go back to Windows 7. Problem was that in Safe Mode, clicking Update & Security does nothing. I was stuck in a Catch 22.
I thought about the oddity of the totally black screen. (Not a BSOD.) Then I had a silly idea. What if clicking on that power save icon had somehow switched my display from the laptop screen to external display mode? Totally illogical. Anyway, I hit shift-F3 to change display and BAM, screen restored!