Do you have secure boot enabled in your BIOS settings?
Was it a total black screen, or do you have flashing cursor?
Do you know if Software Updater ran and updated your working Z17Beta to Z17Core. Maybe you did not notice the update or maybe updated to a new kernel.
If an older kernel works, but latest does not, you should be able to set to always boot the previous kernel. There are posts on here that describe that if needed.
I am thinking your problem could be similar to this (but this time Z17): Zorin core upgrade/reinstall booting to black screen
Check your ZorinOS version using neofetch