https://youtu.be/ZjAlrGzHAkI?t=100 at this point in time of the video we can see the testing method they are using, the wire set, the connections. it is extensive to test using this method ( a job itself). but without extended LAB type analisis , and much more extensive math, and rechecking, and dropping the extensive resistance from bussbars, and connections, and in so much as using extreeme wiring.
The testing method can be slightly flawed.