Can't boot after update

When the computer turns on, it shows a screen with the following text.

At the top it says:

GNU GRUB version 2.02

...then in the box it says:

* Trisquel GNU/Linux
Advanced options for Triquel GNU/Linux

...then at the bottom it says:

Use the and keys to select which entry is highlighted.
Press enter to boot the selected OS, 'e' to edit the commands before booting of 'c' to a command-line.
The highlighted entry will be executed automatically in 21s.

Things I've tried:

When I hit enter with the first or second line selected, the screen goes dark and stays dark.

When I hit 'e' I see a screen with a similar box with 15 lines of what looks like config or code. If I hit f10 from that screen, the screen goes dark and stays dark.

When I hit 'c' a command line, I get a "grub>" command line following some instructions starting "Minimal BASH-like line editing is supported..."

Thanks. The screen goes dark.

Thanks for all the great feedback! I'll post the fifteen lines here this weekend, try things in the Fixing a Broken System link, and report back.

I typed out the following from a screenshot. One of my debug steps was to follow a blog post that had me look at the different drives to see which one had the linux install on it. I think it was hd2,gpt2. I looks like in the below that Trisquel is trying to boot from hd0,gpt. I feel like I could try changing that in this screen, and it's obvious how in places where the value is "hd0,gpt2", but what would I do with parts like "--hint-baremetal=ahci0,gpt2"? Use "--hint-baremetal=ahci2,gpt2"?

setparams 'Trisquel GNU/linux'

recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
insmod ext2
set root='hdo,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 b0fb4364-429c-4573-b0a0-7bddb6bb37ca
else
search --no-floppy --fs-uuid --set=root b0fb4364-429c-4573-b0a0-7bddb6bb37ca
fi
linux /boot/vmlinuz-4.4.0-161-generic root=UUID=b0fb4364-429c-4573-b0a0-7bddb6bb37ca ro quiet splash $vt_handoff
initrd /boot/initrd.img-4.4.0-161-generic

...also, then if I edit that page and boot and it works, do I need to do anything to persist that change? I suppose I'll soon find out!

I tried a bunch of things but without a CD and working through my dad, I was defeated. Thanks for the helpful advice. I'll try to apply it next time I'm physically in front of the computer.