Hi t-rex88
To solve the issue with the flash drive, you can try clearing the meory:
a) Entering Tech Mode
To enter the service mode, press 1,2,3 number keys simultaneously. When the password dialog box appears, enter “1934”
and press the “OK” button.
Once you are in Tech Mode select the options
Test Routine > Others > Memory Clear > "Country"
Regarding the LINUX drivers you can try with the one that we have in our web page:
https://ftp.hp.com/pub/softlib/software13/printers/SS/SL-M4580FX/uld_V1.00.39_01.17.tar.gz
In case that the driver above does not work, it's possible that you may need to contact a LINUX developer to get extra help since HP does not update the drivers for LINUX at all.
Regards.
Knowledge is to be shared.