The firmware is read from the boards, and then compared using the file comparison program WinMerge. The comparison result is shown below:
The yellow sections show areas where there is some difference between the two files, clearly a significant portion of the files are different. A byte by byte comparison shows 12000 bytes (2%) are different between the two files. This is enough to prevent the two circuit boards from being compatible with each other.
What does "Firmware Transfer" mean? Is it REALLY necessary?
The circuit board contains a small program that tells it how to run the hard drive, this program is called the firmware. Firmware transfer means copying this program from the original board onto the new board.
For older drives, this process is not necessary because different circuit boards use the same program. For most drives made after 2008, this process is ALWAYS necessary, because the board contains some unique information about your hard drive.
What if the board is burnt?
No problem. As long as the chip (typically a small 8 pin ROM chip) that stores the firmware is intact, we can read the firmware directly from the chip.