[@AdmrlStalfos19] could always go the “accidentally used some still-functioning old-world technology” route.

Perhaps some pre-apocalypse scientists in the area were working on that “download your consciousness” process, and the character activated a machine out of curiosity.

Then it would be a relatively simple matter to plug their “brain” into some sort of prototype armor or robotic exoskeleton (probably set up in the same facility).