When SOL and linux won’t boot (i.e. like /etc/fstab is misconfigured, which prevents you from booting and correctly configuring /etc/fstab…chicken and the egg type of situation…), you could in theory boot with a live cd or something along those lines. Otherwise, you can, from grub (i.e. grub menu -> find the entry you’re booting with, press e), add in break=premount

For example:

linux /vmlinuz root=/dev/md0 $kernelargs break=premount

This will break into busybox prior to mounting, which is quite early in the boot cycle (you can lookup grub/break to see if there’s anything earlier). Busybox is minimal, but infinitely better than the grub shell (ie. from grub menu, press c; you can’t edit files and chroot or anything from here). From busybox, you can chroot and access your harddrive’s contents and make configuration edits, and try to recover.