Hold on, as a owner of a computer hardware repair shop for more than 10 years I can give you one advice. If you don't know what you are doing, please don't attempt to repair it alone. I've seen "repaired" things that are beyond repair.
Keep in mind that whatever you do with the disk you have a high chance of destroying what was left on it.
Example every time you power up a SSD the firmware will will attempt to do a maintenance even if it's not connected to a PC, those are processes you cannot stop and they can make things even worse depends on the failure you have.

To me it seems like you have a controller chip corruption the way you explained the issued you got, this is the most common failure you get with those ssds. The memory chips should be all fine. I'm not a professional data recovery expert but I can bet on  that was the initial issue you had. I don't know the current situation after the "friends" repair attempts but if the hard drive didn't have any physical damage and just suddenly stopped working then controller chip corruption is the most common what can happen.

There's a possibility to replace the controller chip and the drive has quite high chance of getting back to normal but don't attempt to change it yourself.

If you have taken it to a professional company and they said that it cannot be repaired, the are not a professional data recovery company, or your drive is physically broken and total loss.

On the other side, the company cannot make a full recovery if the drive is encrypted and they don't have the decryption key, most likely every reputable company will require it. You might have a chance to make an agreement to get the raw data on an external drive and try to decrypt it yourself, but the company will not be able to verify if the data was properly extracted. You might end up with a bunch of 0s and 1s that have no meaning even after decrypting the data. You have to either risk the chance of getting your coins stolen, with a reputable companies the risk is lower, or just forget about the coins at all. Trying to fix it yourself won't do the job.

This is what I can tell you from my experience. Good luck with the recovery.