The Mint forums pretty much tell everyone to blanket disable secure boot because nobody seems to know how to make it work, certainly not well enough to explain it to a beginner.
I accidentally checked "install media codecs" on the Mint installation which requires secure boot. Didn't think much of it but something went wrong later on in the setup causing a restart. Well, it left the secure boot stuff in a weird state and forced me to reset the CMOS because nothing was working or booting.
