Lost Data, is Recovery Possible?

Files on an SSD drive that malfunctions are lost, generally without any possibility of recovery. Encrypting the drive makes recovery of file fragments impossible.

The SSD drive on MacBook Pro since about 2015 models is soldered to the mainboard, for maximum reliability in a system that can be subject to multi-G forces just being moved about in an ordinary way. Iif the mainboard was replaced, your files are lost.

The agreement you signed when you submitted your Mac for service spells out that your files are NOT guaranteed to be returned to you, that you have made all the backups you wanted, and that you are OK with that.

Apple provides the really good and free Utility Time Machine, built into MacOS, to back up your files. All you had to do was attach an appropriately large external drive and tell it to GO.

Electro-mechanical devices fail at random, arbitrary, and capricious times.

The most frequent reason for most failures is 'just because'.

Your specific failure is most likely caused by an advanced scientific principle called ...

... 'bad luck'.

Attach your external drive and use

System preferences > Time machine ...

... to turn on Time Machine and specify what drive to store your Backups on.  It may ask to initialize the new drive, and that is as expected.

Time machine works quietly and automatically in the background, without interrupting your regular work, and only saves the incremental changes (after the first full backup). Time machine backs up every connected drive that is in a Mac compatible format. it can not back up Windows format drives.

Time Machine's "claim to fame" is that it is the backup that gets done, because it does not ruin performance of the rest of the computer while doing its backup operations. You do not have to set aside a "Special Time" when you only do backups. When you need it, your Time machine Backup is much more likely to be there.

How to use Time Machine to Backup or Restore your Mac:

Back up your Mac with Time Machine - Apple Support