I just upgraded to 20.04 and the upgrade seemed to have gone fine, but when the computer rebooted after the upgrade it does nothing but sit at "Loading Linux 4.15.0-1019-oem . . .".
I had previously configured grub to force this kernel because of a a bug with my thunderbolt dock in the newer kernels. I've tried holding down shift to get into the grub boot menu and seeing if removing this option fixes the problem, but I can't get to the grub menu. No matter what I've tried the system just flashes the bios screen and then immediately gives me the above message.
Any suggestions of how I can get in to grub to remove that and/or other ways to solve the problem?