Slug nut

Car was in front end smash lhs, repaired fuse box, esp abs lights on left rear wheel speed sensor and abs pump complete with module on it replaced by second hand unit.... car starts when using quick release to get out of park vehicle selects all the gears and is mobile. Brake light switch is magnetic type lights work...
Checked fuses and ground points that are obvious, no voltage drops, all control units responsive on diagnostics. HELP