Can't access WebUI, and automations don't run

After using Portainer to mess with some files in an attempt to get the Lutron Caseta fans to show up in HA, and after rebooting the system, I can’t get the GUI to come back. HASSIO appears to boot fine (from what shows in the console), but no automations run. Samba works, so I’ve copied out all my configs and back-ups… Is there a way I can access the system files so I can copy the un-modified files back? Unfortunately, I didn’t have SSH setup to launch at boot.