Problem: First, I see similar questions but everything points to a blinking cursor. I do not have a blinking cursor but black screen with a (non-blinking) underscore in the upper left OR I am stuck at grub.
Background: Elementary was working fine til yesterday on my iMac (wiped to run only Elementary) until I tried to run a Python script in attempting to install Proton VPN. It didn't work, but I continued to use the computer until I started it this morning and got the black screen.
Actions & results:
1)Start system with power button: Displays "System BootOrder not found" then loads the choices to do: a)Elementary OS> black screen; upper left non-blinking underscore
b)Advanced Options> Recovery Mode> a long output with a plain underscore (non-blinking), can't input anything (pic 1)
c)I can get to GRUB but after running everything I've seen in the past 3 hours on how to fix Elementary from Grub, I can do nothing. I can't get a Terminal screen either to run commands or even a shred or dd command (which is what I want to do at this point).
Unfortunately, I can't reinstall my Mac OS to wipe it all to reinstall the Elementary USB. Secondhand mac has DVD/CD drive but came with preloaded OS which I wiped, confident I'd love Elementary. I DO, but I realized I screwed something up trying to install Proton VPN yesterday and running the software update from Applications.
Any help much appreciated. I've tried all related solutions here but saw none with non-blinking cursor. I'd also appreciate how to wipe or DD or shred this system to start fresh since i already flashed the Elementary install on the disk. But again, it will not load from that (I've been researching for 3 hours and see no way to do that without access to Terminal since I'm stuck in Grub).