Removing encryption from a Self Encrypted Disk on a non-booting system, with OpalSPKey.compmutername.recovery.dat available

New Year's Greetings!

I am suffering from a problem very much like the one described in this forum post: de.community.dell.com/.../18317

What can I do to restore my Latitude E6430 to a bootable state, or at the least remove the encryption and access my data?

I have the OpalSPKey. .recovery.dat file available.

Best regards,
Dave