blank screen during "System Upgrade"

Looks like I picked the wrong day to attempt an f17->f19 upgrade...

fedup-cli completed normally.

Verified grub.cfg updated w/ "System Upgrade". T'was.

reboot and select "System Upgrade" from grub menu.

Was presented w/ a pulsing "F" and progress bar for maybe 10 sec, then the signal to the monitors went away and I'm staring at a dark screen while the system appears to be, uh, "upgrading".

It's still working on it..., I have no idea what the end result will be, but I'm guess'n it's not good.

First: since I'm assuming that the machine will just "stop being busy" after awhile, is a hard reset my only option for shutdown/restart? Just verified, no VTs available.

Assuming the MBR and grub.cfg remain more or less "intact"..., there is an instance of Ubuntu 12.04 that should still be bootable..., so that's the "running" OS at this point apparently.

Will I be able to recover this by burning some kind of Live DVD and using it to patch the problem when a fix becomes available?

Sorry for the basic questions..., but I've been both very reluctant and lucky over the years when I've done upgrades..., so I've never had to actually recover a botched upgrade.

Help!

P.S.: It's a desktop box FWIW.