If you can boot, put a 3 at the end of the boot syntax before you boot
and run the upgrade again. See if that helps.
I run multiple computers for testing and there are 3 computers on my
desktop with amd and intel and each one has 14.2 installed, none have
had boot problems. I say this to let you know the problem is probably
somewhere between the chair and the keyboard. But I really don't know a
lot about much of anything. :)
--
Jimmy Johnson
Slackware64 Current - AMD A8-7600 - EXT4 at sda6
Registered Linux User #380263