Well, if you have 0 Ohms on 47 and 48, that would tend to indicate that your incoming AC voltage is shorted to the chassis plate somewhere. If, by chance, you accidentally measured with the power cord plugged in, then you would just be measuring that the neutral of your incoming AC is properly grounded at your breaker panel.
Otherwise, there's just the wiring at the IEC socket, power switch, and those two terminals that is otherwise completely isolated from the chassis. There isn't a whole lot to check here to verify that there aren't problems.
-PB