Absolutely nothing. As copyright law has nothing to say about boards. About the software in the ROM?
The point is copyright restricts performance, distribution, and modification, not just copying.
The first sale doctrine has been used to establish a precedent that allows you to re-sell copyright works you have purchased. The right of the copyright holder to make the copy exercised by the first sale, flows; that is: this allows you to resell the work, the first sale permits it.
But there's a problem here.... what happens when you have an unpublished copy that was never sold to anyone; there is no 'first sale'; therefore, the first sale doctrine does not apply to this ROM you have recovered.
And there is no first abandonment doctrine I know of, that says the copy of the work of an author who abandoned a copy of the work, or accidentally misplaced a copy, or who accidentally leaked a copy due to employee misbehavior, or subcontractor misbehavior -- enjoys a right to be redistributed.
Therefore.... there is no right to distribute the work that is flowing to you.
In other words: salvaging the ROM, and reselling it without copying, might be infringement. There is no precedent I know of which says that is allowed, and it encroaches on an exclusive right protected by the copyright statute, that would tend to suggest that redistributing it would be illegal (even though you haven't made the copy -- and the copy may have been legal to make, it was never "infused with a right" to be redistributed, since there was never a first sale).