I have a Seagate Barracuda 7200.11 2Tb SATA ST32000540AS that went from NTFS to RAW in it's USB enclosure (Freeagent).
When I connect to mb SATA I can see the RAW volume in Windows.
When I run testdisk, it flies through at lightspeed reporting every sector as bad.

Sounds to me like a access problem, it doesn't seem like the head is travelling across the disk (too fast).
When I boot I can hear the drive spinning up so I know the motor is OK.
I also took a look the head isn't stuck.

I wonder if fixmbr might help? Does it work on RAW volumes?

If by take a look you mean you opened the drive (not the enclosure, but the hard drive itself) that's not good at all. (that is unless you are really curious about hard drives and you don't mind ruining this drive and loosing all the data)

If you were (at least before you ruined the drive) seeing a raw partition that implies you can see the MBR / partition table. But you may have many bad sectors. Were all the sectors bad, or you just saw a lot of them? fixmbr has no purpose for your case, forget that tool for now.

You should (if you don't want to send the drive someone for recovery) try to clone the whole drive to somewhere else and then use data recovery tools on the recovered image. If it shows as raw the filesystem is corrupt and needs data recovered from it (rather the mounting the volume and just reading it normaly).

Clearly the hard drive is having hardware malfunctions. So any operation that writes data (like fix MBR) will only further complicate the situation.

I really recommend that you bring the drive to a data recovery company where they will have the tools to properly diagnose what's going on with the drive and safely extract the data.

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Data Medics - Hard Drive, SSD, and RAID Data Recovery Service Company