My mac mini downloaded a security update yesterday. Since then, I have major problems. I spent almost eight hours trying to fix them last night. I used to run OS X from a SSD connected to the computer by a Thunderbold cable. Thunderbold stopped working altogether. Apparently, there is also a serious problem with a new driver for thunderbold that was released a couple of days ago. What got unsuccessfully updated was the MacIntosh hard drive. Nothing worked any longer. I just saw the spinning wheel going on forever. Tried to boot into Time Machine to restore the system from it. Didn't work. Tried all kinds of other things, they did not work. Finally I connected the SSD with USB 3. I could start it, but the MacIntosh Hard Drive could not be accessed. Tried to install Mavericks again. The installation was stuck at "2 minutes left" forever, and ultimately did not work.
At some time during this process, the Mac app website must have gone down. In any case, I could not download Mavericks to do a clean install from a USB drive either. I don't remember what else I tried that made the problem worse. I stopped working on it at 4:00 AM.
I followed the instructions I found on the internet (unplugging the monitor for more than five minutes, etc.) But it did not fix the thunderbolt issue either.
It is frustrating, to say the least. I am used to this kind of trouble from Microsoft, not from Apple. I wonder whether these are some of the first signs of sloppiness, resulting from Steve Job's absence.