Foxconn MB in a clone case. Multiple failures on drives. Finally, cleaned pins on MB - knowing just how some of these modern 'gold' connectors are made.
I've had a diamond relay file for 40 years, and I brutalized the metal surface, but at microscopic level of course.
Many reconnections of the leads, which sometimes cleans the metal, but it obviously failed to do so. After filing, no more problems at all.