There is no "first sale" for a non-transferrable software license -- even when you get it as a part of a physical good. You are confusing licensing with copyright, which is a different thing entirely.
When the second sale occurs, the seller must still obey the terms of the software license, which means the seller must give the end-user a full license which includes the ability to demand the source.
If it were otherwise, the GPL would be meaningless. Instead of the many BusyBox lawsuits, the companies could have "sold" their boxes, "bought" them back, then had no GPL obligations.
Lastly, without the GPL you have no software license and have no right to run the software.