I would assume they either provide a device that just talks to the drive whether the drive likes it or not... or... they remove the PC board, and replace with a board with correct bios... the bad boards are then returned to Seagate, the roms are replaced with SMD rework, and then are used to make repairs to additional drives.

A freinds disk just croaked, even though I gave her advanced warning to fix it, she didn't get around to it, so... poof.

Guess she will get Seagate RMA and see what happens.