I finally was able to get update 11.1 installed!
I tried many times the solutions stated here. Booting into recovery and running disk utility. This I've done daily in hopes that it would finally work. I never got an error on disk utility.
I tried running the update several times, let it run and the furthest it would get to was to 10 mins pending in preparing the update.
I even found a thread somewhere that suggested running the update from terminal, running this command:
sudo sh -c "softwareupdate -ia && reboot", but on this method it would get to a maximum of 75% download.
I tried mostly at home, I even tried at the office, as someone suggested.
Today, I tried going into safe boot, starting the computer while holding the shift key. It finally worked on the second try. It took a very long time doing the download, but then it went to 15min remaining, then quickly to 10, stayed there for a while. I was about to throw in the towel when the progress bar started moving and it went to 5 mins. I decided to let it run to see what would happen and it finally went to done and the popup indicating that the computer would restart in 1 min came up. After that, all went as it should have since the beginning.
I don't know if it was luck, but one thing I did notice while I was in safe boot mode, is that the fans never kicked up as it would each time I ran the update before.
I've never had anything like this happen to me ever, I've been using Mac ever since they migrated to Intel 15 years ago.
Hope this helps someone.
