Normally they shift all your data a few hundred megabytes later in the drive so they can use the area at the start to store their "drivers" (ie. The software they encourage you to install on your PC to offer backups, encryption, cloud storage, antivirus, and other crapware of dubious value). Sometimes the casing firmware emulates a CD-ROM device and offers this data because the OS will autorun software from a CD. Then when the software is installed, it switches to hard disk mode to present your actual data.

The external drives which offer 'encryption' nearly all do it through software on the host PC and sometimes the drives built in encryption (did you know all modern hard drives can encrypt data before writing it to the platters? - nobody uses it because you can't tell if the drive really is encrypting your data or just pretending to).

> Normally they shift all your data a few hundred megabytes later in the drive so they can use the area at the start to store their "drivers"

So, if I'm really lucky I can use testdisk to find the partitions and just mount it read only from there without involving a recovery company?

Yep. As soon as you find the sector number of the start of your data, you can use "losetup --offset xxxxx" to use it like a regular disk again. I think there are even SCSI commands you could send to permanently shift the start of the disk. Or you could just dd all your data back to where it ought to be.

I read a bit more and it seems some models has encryption mode (by default using an empty string for a password it seems.) There exist at least two projects to get data from those MyBooks so I'll try those if the simple version doesn't work.