Bought a used ledger nano s from Amazon / Ebay. How do you factory reset the Ledger Nano S? I just bought a used ledger nano s from amazon and ebay. What is the best method of wiping this device and factory reset it? What are some other precautions before using this used device?
From the Nano S Configuration Guide:

How to erase or reset your Ledger Nano S?
If you acquired a second-hand Ledger Nano S, or if you want to create
a second wallet, follow this tutorial to learn how to reset your
device first.

Connect your Ledger Nano S
Enter a wrong PIN code and validate by
pressing both buttons
Repeat the 2nd step two more times
Once your Nano S displays the message &quot;Your device has been reset&quot;, press both buttons until the &quot;Welcome&quot; message is displayed, or disconnect and reconnect your device.

Then you will be able to restore a wallet or create a new one.

Also keep in mind that your device may have been tampered with and does not contain genuine hardware. You will want to read this guide to ensure that your hardware is genuine.