After installing Thunderbolt Firmware v1.2 on Mac Mini (late 2012), Thunderbolt works no longer and neither does my thunderbolt to VGA adapter.
After install I get this message
Mac mini, OS X Yosemite (10.10.5), Late 2012
If you don't already have a current backup, back up all data, then reinstall the OS.* You don't need to erase the startup volume, and you won't need the backup unless something goes wrong. If the system was upgraded from an older version of OS X, you may need the Apple ID and password you used.
There are ways to back up a computer that isn't fully functional. Ask if you need guidance.
If you installed the Java runtime distributed by Apple and still need it, you'll have to reinstall it. The same goes for Xcode. All other data will be preserved.
*The linked support article refers to OS X 10.10 ("Yosemite"), but the procedure is the same for OS X 10.7 ("Lion") and later.
Did you ever find a solution? I also have a Late-2012 MacMini with the exact same issue. I've tried booting from the original HD with a clean OS running 10.8 and have the same issue as I do with my SSD and El Capitan, so this won't be resolved by a clean install.
A few months ago this update popped up in the AppStore while I was running Yosemite. I applied the update and saw the same Terminal-style text at reboot. System Preferences > Hardware > Thunderbolt now shows "Thunderbolt: No hardware was found.". To make matters worse, AppStore keeps trying to install the update! I followed Thunderbolt Firmware Update 1.2: Keeps reappearing and Thunderbolt ports and Target Display Mode may not work - Apple Su… to no avail. SMC and PRAM resets also made no difference.
The system is out of warranty so I'm stuck using USB 3 and an HDMI monitor now. Very frustrating!
After installing Thunderbolt Firmware v1.2 on Mac Mini (Late 2012), thunderbolt works no longer and neither does my thunderbolt to VGA adapter
