Every G-Technology external drive has two components: the Thunderbolt/USB bridge board (converts SATA to Thunderbolt 3 or USB protocol) and the internal HGST or WD hard drive. The first diagnostic step is determining which component failed.
If the bridge board is dead but the internal drive is functional, we extract the HGST/WD drive, connect it directly to a SATA port, and perform a standard data copy. This is a simple copy tier recovery ($100). No clean bench work, no head swaps, no firmware repair.
If the internal drive has failed (clicking, beeping, not spinning, firmware corruption), the bridge board is irrelevant. We bypass it and connect the bare drive to PC-3000 via SATA for firmware-level diagnostics using the WD Marvell or HGST module.
G-DRIVE Thunderbolt models use Intel or Texas Instruments Thunderbolt controller chips on the bridge board. These controllers handle protocol translation and sometimes power delivery. The bridge board is separate from the drive and does not contain user data. A failed bridge does not mean the data is gone.