What type of cable did you use? Water could have seeped into which cause a bunch of weird issue because the resistance on the wires goes all wonky. I’m not sure if you have access to a cable certified like a Fluke, but if you do I would use that to test and it will most likely tell you your issue. I highly doubt it’s a grounding issue because you’d issues like that in large buildings where the power is on different phases or technical power.