Yes, he was court-martialed and discharged from the Marines for bad conduct: Court Document
A long time ago... We don't know the details.
Actually, the military appeals court document you linked provides enough information. The summary says his crimes included writing multiple bad checks, false use of an SSN, dereliction of duty, etc.
Receiving a fine, reduction in rank, confinement, and a BCD was not especially severe, especially since he was a career Marine (SSgt).
Thanks for posting this link since this information about his military career, along with reports of citizenship in multiple countries, paints a completely different picture of him and his character.