Car Won't Startup!

I have a 1999 Honda Prelude Type SH that has 116,000 miles on it. The problem is that the car won't start. The problem happened overnight. The instrument panel wouldn't even light up upon turning the key. No clicks, sounds, nothing. The car was able to jump start, but once you turn the key off and try the start the car again, same thing. Nothing. The battery, battery cable (positive), and the alternator have been replaced. Same result. Tried 2 other batteries but same problem. Fuses checked out fine. But the car can still be jump-started! The voltage across the battery terminals registers around 12.6V. When revved up, the voltage does not change. This was the case before and after the new alternator was installed. No one can figure out what the problem is so any other suggestions would be most helpful.