Try resetting your BIOS to default settings then disable secure boot again. The mok issue should likely be due to an issue with secure boot and the iso.
Here’s some more information about import_mok_state(): https://www.reddit.com/r/pop_os/comments/16tf1vl/something_has_gone_seriously_wrong_import_mok
If you are unable to solve your issue, try checking online for solutions.