Mojave, Mac Mini late 2014.
Tried to install Supplemental Update 2, but it froze. Progress bar was only 1 cm. After 2.5 hours, forced it shut, then used CMD+ALT+P+R and now progress bar slowly got to the end, filling entire bar... and stuck.
Forced it shut again, then tried to reach both Recovery Mode and Safe Mode. It will not go there, just keeps installing.
It has been several hours since leaving it to do it and no changes at all. Progress bar is full, but nothing happens.
At this point I just want to break free from installation screen and get to my files. Is there any way to do this or do I really have to go to technican?