You left off the most important number: ammonia. In a cycling tank, it's quite likely that you don't have any nitrite yet as the bacteria that process ammonia and changes it to nitrite haven't developed yet. Ammonia is also the most toxic and deadly. That would explain why all the fish died at the same time: the ammonia built to a level that poisoned them all. If you don't have a kit to test ammonia, get one quick. And stay away from the strips as they are too inaccurate.
When you say you started the cycling all over again, I'm a little confused. If you have fish in the tank, your cycling all the time until the bacteria has developed to handle all their waste. Did you change the filter or something? Don't ever change the filter until it is worn to the point that it is coming apart. The bacteria colony lives in the filter so when you change it, you throw most of your bacteria in the trash.