I took a CARES Act distribution from my 401k. What exactly is considered repayment of the withdrawal? I understand that 401k payroll deferral is not considered repaymen

The account from which I made the withdrawal has since been closed.  Does the repayment has to be in the form of "new money" being contributed to an eligible retirement account?  Alternatively, rollover/transfer money from another account to an eligible retirement account?

Contributing "new money" would likely come from post-tax money. In the event the taxes were already withheld from the distribution, it appears "new money" from out-of-pocket contributions would lead to double taxations.