The TC58NC6623 / SSS6698-BA combo is reliable when working, but a power surge or unsafe eject can corrupt the firmware easily. Luckily, unlike Monolith drives (where the chip is glued to the board), this controller plays nice with MP Tools.
Getting a TC58NC6623/
It is vital to understand the nature of the MPTool repair. This process is destructive. tc58nc6623 sss6698ba mptool work