Have you had luck recovering videos from a formatted card?

So I accidentally (=forced by North Korean soldiers. long story.) formatted a card while it was in a GoPro Hero4 Black. The app now says there is no media on the card.

I usually would try recovering the videos on a mac using the usually excellent photorec but the card wasn't even readable without being initialized, which I didn't want to do. I subsequently gave it to a local file recovery company who threw in the towel. I am uncertain as to how hard they tried.

I realize this might be the end of the road for the footage on this particular chip but thought I'd give it a last shot here. (I did contact gopro support but have not heard back.) Have you had luck recovering videos from a formatted card, not just a card where a single video was deleted?