First and foremost cheers guys!
This is my first post here and I'm hoping for a "happy ending"...

Hope to continue reading the forum long after my problem has been resolved (time-willing) and to learn as much as possible in order to avoid future problems and be able to best evaluate any given situation.
So, to the point.
I had the misfortune of acquiring a second hand Power Supply for my system that would allow me to take my current power Supply and finally assemble a long awaited backup server.
Oh irony of ironies, that very same Power Supply (bought recently) ended up killing my 4 drives before I could even backup a single file.
The Power Supply is a Seasonic X-560W Gold fully modular. What I did not realize at the time I was assembling my system with this unit was that amidst all it's cables came a rogue one. A cable that was connector compatible yet did not have the same pin-out as the Power Supply.
Long story short, I zapped my two SSDs and two HDDs with 5v on the 12v line, 12v in place of a ground, and a ground where there should have been 5V. So I got a very long dreaded whiff of burnt electronics.
Tried the HDDs on another machine and they power up and spin but are recognized at all. In my mind this is an electronic failure due to be repaired by a PCB swap as I had done successfully a few years back with a (already then) very old Samsung 40GB Drive. Searched online (ebay) for replacement PCBs for each of my HDDs and found what seamed to be the best match for each. I order them both, from the US, circa 100€ ($135) shipping included.
I got the PCBs and swapped them out, still nothing. Did a little more digging and found that these drives require the original ROM (firmware/bios) to be soldered onto the new PCB, which I did (had professionally done actually, not too good with a soldering iron).
Drives are "somewhat" recognized. Bios does not detect the Drives correctly and will not write to the screen their model during POST but it detects a drive present.
Under windows 7 (64 bits if it matters at all) disk management will pick the drives up as not initialized which I reckon may have to do with some other ROM that was not swapped. Didn't find this too troublesome as initializing them would not prevent me from recovering the partitions and the data therein.
There is however a little problem, when I try to initialize them (still in disk management) I get the following error message:
"the request could not be performed because of an I/O device error"
To me this is vague, to the apt this probably tells them all they need to know.
I reckon this could be a minor problem with the adaptation PCB with a quick fix and if I could avoid paying upwards of 600€ to 1000€ for something I could do on my own, I'd very much prefer that. If, on the other hand, you think this is beyond "home repairing" and are willing to suggest someone I could send this drive to that is both skilfull and .... affordable, I shall be inclined to do the latter.
So as to not make this topic too confusing and even though both drives have the same problem, I would present one case at a time (photos of the drive label, original and replacemente pcbs, close-ups, etc). I just don't know whether to present the one with the most sensitive data first of last?
I'm lay my Drive's fates and the data therein contained in your hands.
Thank you very much.
Regards,
Pedro Vouga
Ps - Sorry for this seemingly endless "rant"...