Stuck on GRUB command prompt after regular kernel update

You don't need a live CD to solve this.

Type:

grub> ls

Here you should see a list of devices/partitions. Now we must find the partition that contains "/boot"

grub> ls (hd0,gpt1)/

The slash at the end is necessary. You may see "msdos" instead of "gpt". If this is the right partition we should see:

boot etc root bin ...

Type:

grub> set root=(hd0,gpt1)

grub> linux /boot/vmlinuz...(Press tab and choose the last working version) root=/dev/sda1

grub> initrd /boot/init...(press tab and select the same version as above)

grub> boot

This is just an example, you should modify it accordingly.