Anything found possible
Anything possible is going to be looked at somewhere. If it's also practical and affordable, it will appear everywhere.
If I had the test equipment, and I were seeking to break into a device that wiped its memory after, say, 10 attempts, I'd buy a similar device and instrument all of the reset and I/O. I'd be looking for [pins] that only changed status or state on the 11th attempt – and then I'd pull it high or low or provide the normal signals to see if that was the controlling input. Not easy, and for most of not affordable, but certainly practical if you've got the money, the time, and the lab.
That's probably not what the FBI or their helpers did, but it's the first thing that I would have thought of. Then again, I have a different way of thinking. Just ask anyone who knows me!