Hi,
I have a Seagate ST3000DM001 3 TB SATA hard drive (I'll refer to it as Drive A). When I switch on power, PCB (100664987 REV B) gets very hot and drive does not spin. I bought another working hard drive (I'll refer to it as Drive B) with same Model, PN and Firmware. However SN, Date and Site are different from Drive A. I took out Drive B's PCB and fitted in Drive A. But it didn't work. Then, I swapped the 8-pin BIOS chip from Drive A's PCB to Drive B's PCB using heat gun. But, to no avail.
I have noticed that the BIOS chips on both drives are not identical. I was expecting identical chips but the one on Drive A is "cFeon S40-75GIP" whereas Drive B has "Winbond 25040XXXXX 1306". Does that make any difference?
Now I have 2 situations.
1) I have Drive A with Drive B's PCB having Drive A's BIOS chip (cFeon) on it. In this case, there is no sign of life so far.

2) I have Drive B with Drive A's PCB having Drive B's BIOS chip (Winbond) on it. In this case, PCB gets very hot after I power on Drive B.

Definitely, I want to recover data from Drive A. But the newly swapped board won't power up. On the other hand, Drive B has Drive A's PCB but it is at least signalling (by heating up) that there is something in it.
I have also come across many posts on TVS diodes relating to power issues. I can't see anything burnt on both boards. Should I try something like that?
I have highlighted two TVS diodes (In my opinion, please correct me if I am wrong) with red and yellow colors in first image.
Thanks.