Q: problems with osx sierra upgrade

I just tried updating to OSX Sierra today, & I'm having problems.  I downloaded Sierra and that seemed to go OK, but when I went to install it, my computer hung with an error and then crashed.  I wasn't close enough to see what the error said.  It restarted and now only comes up with an install progress bar.  The install gets stuck at about 80% complete (for 3+ hrs).  If I click any key while it is stuck, I get kernel panic errors printed over the install screen.  Then, a few seconds later I get the dreaded 'your computer restarted because of a problem'.  This same thing has happened 4x now. 

All of the troubleshooting discussions I've found have instructions on what to do by using various system menus or applications... or booting into safe or recovery modes.  But I can't access anything outside of the install progress screen.

Anyone have ideas?  My computer is a big paper weight right now.  THANKS much in advance.