Of course, the first thing a drive recovery service does is swap the
logic board from a working drive....

Mark, that will not recover his dead drives, gent already said he placed
them into another computer and they were still not operational. Only option
is to find identical drives and try swapping the logic pcbs, still modrately
questionable. Third, but most expensive, is to send the defective drives to
a recovery company who have the techniques to recover the data.