Re: Power Distibution Board - Broken stud
 

Here is a data point: We have six of these boards on various robots. We have one a broken stud. Relatively untrained student screwed on a 1/4-20 nut with an experienced mentor looking over her shoulder. Definitely operator error in our case.

We are now powering that PD board through a Wago connector for a test bed.

Re: Power Distibution Board - Broken stud
 

The PD shanks are fragile, when compared against steel M6 screws. The PDB doc (here) states, on p.7, that the shanks can shear if torqued to more that 3.9 N-m. That's about four pounds of force at the far end of an eight inch wrench. Not nearly as much torque as is typically recommended for steel M6 screws -- about 10 N-m for Class 8.8 or 15 N-m for Class 10.9.

However, the OP clearly stated that the person with the wrench was a veteran electrical mentor guy. I agree this one is probably just bad luck. One of the best students on our team had similar bad luck a couple of years ago.