YOU ARE DEAD TO ME.
Interesting question, I wouldn't buy a hardware wallet from an uncertified seller because it would make me nervous, and the entire reason for me buying one was so i did not wake up in the middle of the night from a nightmare about some cunt in belarus jacking all my shit.
With regard to the possibility of used nano ledger s potentially being insecure: It is definitely possible, but I would imagine it is unlikely. Obviously your best bet is to speak to the ledger bros and do whatever they tell you!
<3
I will make a new alias and win back your heart beaky!!
...an important security detail from ledger,
Source: https://www.ledger.fr/2015/03/27/how-to-protect-hardware-wallets-against-tampering/