Help!!!!! iMac not functioning properly after 12.10 updates (Safari and Security update for Mojave). Beachballing, freezing,

Hello Torreypines, Thanks so much for replying. I was thinking the same thing "being too hasty in pulling the power" but the black screen was there for more than five minutes and I was not seeing the normal black screens with the apple logo and the progress bar, I was just sitting there with a completely black screen and nothing, which is why I thought it failed and pulled the power. I contacted Apple for support since I could not find both download links on the apple site after the manual reboot and all the issues I had. We ended up spending an extended amount of time on the phone since support wanted to take a different approach rather than try downloading again. The long and short of it was after running diagnostics and running first aid and still having the same issues with some improvement in safe mode, we re-installed Mojave. After the reinstalling my OS, the updates automatically came up. This time I decided to install each one individually beginning with Safari which installed and completed in no time. I tested it and it was running better, so I went forward with the second update - Mojave and it took far less than half an hour with no frozen black screen at any point (just the typical multiple black screens with the Apple Logo and load bars as it progressed), and she booted right up as expected. After installing I ran EtreCheck since I am still having some issues and found MicroSoft pushed some updates as well and I did not realize it since I no longer have the same visibility as I did with High Sierra (I could see every available update as it rolled out in the App Store and decide if and when I wanted to install them), I am not a fan of the newly designed App Store in Mojave and need to look at my settings to see what I may need to change so I am alerted instead of an auto install from other developers besides Apple.

Hello William,

LOL, way too optimistic is an understatement ".I'm not sure as to how the "minutes remaining are calculated, but it appears to be WAY optimistic! Lol!"

After dealing with Apple for about six (6) hours not the phone, running diagnostics, first aid, etc. they determined re-installing the OS was the way to go and that is what I did.

Mojave was still calculating the install time after and hour and forty-five minutes after I started the re-install process, so on a touch base call Apple asked me to push the power button and it gave me a number finally (40 min). After an hour, I did the same thing, it said 17 min, well okay, so for the fun of it, I hit it again within a minute and it said one min remaining and I about laughed myself off my chair (it was either laugh or cry after spending an entire day on this unplanned "event") since I know how long it took to install this OS the first time I did it and just laughed and went and did other things and came back after a few hours and it was done.

After completing OS re-install the updates were pushed to me again, and I installed them one at a time - Safari was the first and it was done immediately, so I moved on to the Mojave update and it took less than half an hour and I did not get a frozen black screen this time, just the normal multiple black screens with the Apple logo and the load bars and she booted right up no problem afterwards ;).

Thank you, to all that replied to my question. I really appreciate the responses and assistance.

Lynn