I think unplugging was probably the smart thing to do. The only thing that it seems safe is to contact a Data Recovery Service. That's not cheap: I found this:
The hourly rates for a clean room data recovery professional in the US typically cost anywhere from $100 to $300 per hour depending on the location, skill, and educational background of the data recovery engineer.
Apparently $200 is typical.
There are data recovery apps out there-- way cheaper, but not as reliable as taking advantage of a "data recovery engineer." At the App Store, none of those apps have many stars-- lots of disappointment. They seem to cost around $40.
Good Luck…