When I try to upgrade to 10.12.2, my mac mini reboots to a white screen. The mouse is responsive, but nothing is drawn. In previous upgrades, I could get past this by holding SHIFT for safe mode; and then the upgrade would complete. Not this time. There are no USB devices except the keyboard plugged in. I've reset PRAM/NVRAM, no change. I can boot to recovery. Any other suggestions?
I experienced the same white screen issue after updating to 10.12.2 and was forced to restore from a previous time machine backup (after trying to repair the drive, resetting the PRAM/NVRAM and booting safe mode failed to work). Stupidly, I tried updating to 10.12.2 again on the restored version and during the reboot process it went back to the white screen.
Don't install 10.12.2 if you have this issue.