Re-Cycling - Possible?

Have him start with a hardy fish. That way if it isn't cycled the fish should be able to make it threw, or if not at least it wasn't an expensive fish.

 

given the timelime you gave (and the fish (dead for part time) for at least a week in the tank) i find it highly likely the cycle went through its steps.

It's one reason I recommend waiting at least a week before adding another fish - make sure those numbers stay 0. Then add only one fish (this is a test fish, so plan accordingly with your money) and watch params for another few weeks.

If params go nuts, then you got a cycle to deal with. If params don't budge or if they spike slightly and come back to 0 after a day or so, then in another couple weeks fish 2 can be added.