Check the wires where they feed into the electronics enclosure.
I noticed today the lip around the opening to the electronics enclosure and cover are sharp. My ground wire and A axis cable we’re rubbing up against the sharp metal I’m beginning to fray.
Adding a rubber gasket around the opening fixed the issue for me.
I had an 2016 machine that had a rubber grommet around that hole. I replaced the controller with one for the BitRunner and got a new case. I transferred the rubber grommet to the new controller. On my new controller enclosure the wires come out the top (XXL). I bought a used XL and the previous owner pushed in a piece of open cell pipe insulation around the wires.