Yeah, Safe Mode is still there. You'll have to google what F key you need to hit (some are F2, some are F8, etc) as it's booting up to get to the selection screen... seems like every machine is different.
Another method (while in Safe Mode) I would have tried would have been to go to Control Panel and have your machine scan for the updated driver on that vid card, and if it didn't recognize by itself that it needed the Radeon driver, uninstall it to prompt the redownload. Sometimes a reboot is needed to kickstart that process.
BTW, did you attempt to change video settings with the Win10 driver? That would have been the first thing I would have tried. Sometimes they're not very self aware and need to be tweaked.