OK so this board is one that pretty much kills any chance of a DIY pc board swap. The adaptives, code unique to each particlualr drive, are in a ROM area inside th MCU( the large Marvel chio with the big M on it.
In teh top picture, toward the lower left corner of the board are two components marked D3 and D4. These are teh transient voltage surpression Diodes. Their purpose in life is to protect more sensitive components from voltage spike by conducting all current to ground when their threshold voltage is reached. This threshold is generally only a few tenths of a volt over teh circuits normal level, a TVS on the 5 VDC line may have a threshold of 5.5 - 5.8 volts. Normally when the spike is sensed, the diode conducts the current direct to the ground and when the spike dissipates, they return to normal function. If the spike is too large, then the diode can fail. Many times that failure is obvious, cracking and scorching, but not in all cases.
The only way to rule this out completely is to test them with a voltmeter in diode test position. They should be open one way, short the other. If shorted in both directions, then teh device has failed. The good news is if it fails, you can simply remove it from teh board, and the drive should function again, allowing you to copy out your data. The downside is without that TVS, your basic protection is gone, and another spike will likely fry the smooth motor controller chip, as well as the preamp inside the drive on the head stack. In other words, this is an acceptable way to run the drive long enough to get your data, it is not a long term fix to the problem. Also, removing the Diode will void the warranty on the drive. If it is failed tho, it usually gets your data back.