Serial Number Check

I purchased an Era 100 from a big chain electronic store in April. The box was factory sealed when I picked it up

Then I sold this factory sealed box to someone on  May 5th (Note that i have never opened this box). Few hours later this person contacted me back and told me the unit in the box is a used One Gen2. 

I can think of 2 possibilties:

#1: Someone at the electronic store swapped it before I bought it;

#2: The person who bought from me is not telling the truth.

So I'm just wondering if there is a way to check when this unit was activated. If it was already activated and used before May 5th, then we know it's #1, and vice versa.

Any help is appreciated. 

Serial number (ERA 100)

A100 2301LV *****************

Serial number (One Gen 2)

A201 1909CP *****************

Moderator edit: serial numbers recorded and removed