Complete power loss

I have 2000 Infiniti QX4. This am the car started nicely but a minute later went completely dead. There are no lights, no power, nothing. Battery is good. Fuses are apparently good, too - per car shop mechanic ( I don’t know if they truly checked them). I doubt this is ignition switch, either. Emergency lights are NOT working, either. Simply it looks like a car without a battery.

The mechanic was able to start the car by connecting power to a power box, he says. He thinks the problem is in corroded wiring. They want to replace the whole engine harness plus starter.

The problem I have with it - I don’t believe this is going to solve the problem.

ANY IDEAS???

You probably have some bad connections and something is grounding out your battery and draining it. Have a good mechanic check it out; I doubt if you need to replace all the wiring on such a new car.

Thanks for advice. The battery is not being drained out. It is actually still good.