there is still something wrong in the trailer. If the ground was broken / gone in the cord, and the trailer "power units" are correctly wired, it is unlikely that there would be any issue that is "shocking". If the neutral was gone in the cord, then IF it was plugged into a gfi at the house, it should have trip as the OP indicated there were running systems in the trailer. Somewhere some neutral is "touching" a ground. Likely, one issue was the cord had a "broken ground" but there is still another issue.