I wish that I could remember what we use to do when old things didn’t work on new Macs. It has been many years, but it seemed like from desktop you clicked Go and utilities and terminal maybe and you could start anything on a newer OSX from there by using Legacy Drivers that were still in your machine but not accessible. Sorry I couldn’t be more help, but it might be worth a try. Also you had to do it every time you booted. Good Luck.