Electrical question

Wa8xym- had something similar happen. At a seasonal rv park, when caretakers came to me asking for my help. One of the campers had no power. Did some testing and found that all three wires on the cord end that had just been replaced were in the wrong place. Hot was on the green, ground wire was on the screw that should have been on and white was where the black should have been. This was making the whole trailer live, but it was blocked with wood creating an insulation barrier to ground.

Found it by testing from trailer ground connection point to actual ground. Literally stuck one meter lead into the ground, and read 120V from trailer ground to real ground.