My ST3400620AS was pulled from my system and I dusted it off knocking off a few transistors; clumsy me!
So I ordered a PCB replacement... both are a 100435196 Rev. A boards
What I have: ST3400620AS 400GB SATA 9BJ144-308 with Chip #: V520AA / FW: 3.AAK / Site Code:SU with a Date Code: 08237
What I got as a replacement: ST3400620AS 400GB SATA 9BJ144-308 with Chip #: V520AA / FW: 3.AAK / Site Code:TK with a Date Code: unknown
The system boots but after awhile trying to recover the data; the drive goes offline

Could this be due the wrong Date Code or Site Code... or is this a firmware issue. I am told that I could remove the BIOS off the old and replace it on the replacement board
Kindly open for suggestions