No power.. Ammeter questions.

You would be wasting time with a multimeter, that ammeter is toast. Most ammeters have poor connections from the studs to the internal "guts" which is sort of a shunt and the meter itself, 'a brass strip.' The studs actually rely on the compression of the "sandwich" from the nuts. Any looseness and heating causes MORE looseness and heating, which ends up as you see

Also suspect a problem in the wire ends themselves.