Without analyzing the drive (HDD ONLY WITHOUT BRIDGE) it is difficult but as it is an already seen movie , can perfectly be head/firmware problem (one head at least) . Have to check the read channel first , rule out ROM , pcb and then heads and then the entire HDA based firmware. Final problem (the least) deal with encryption. The problem is how , safely , at user level - don't have an answer , unless you borrow the needed gear. Another question : is data so valuable ? probably the cost of recovery at this stage is not the end of the world.
This is what I would do... in lab.

Thanks BlackST, you are right.

Analysing the HDD only (without the bridge board) directly connected to the MOBO via SATA port is one thing I have not try.

It is not because I don't want to, but I don't have the computer to test with. (the only desktop I had is very old).

Let's say if I'm able to test, and the HDD do get detected at the BIOS level, does this mean I can rule out the head problem?

Yes and no depending on your very case. Note that it is not safe to test such ENCRYPTED hdd 'live' on PC running XP and above. Dos based test with MHDD or with a dedicated hw tool is much more safe (possibility of writing/initing).

p.s. you are not sure yet if it is fw, heads, pcb or a blend. just guessing...

A DDA + related tool can test the read channel in 1 minute with 99.99% certainty, if you have the right tools the entire pcb is tested ROM included (need some looking by human), entire diagnose without opening the drive takes 1 - 1 1/2 hour, to me. Can't you find someone in your area with the necessary gear ? (unfortunately the 'gear' is in the $100K range)

I see, understood.

If that's the case, I will bring it to another data recovery center for a second opinion / diagnostic.

Thanks for your input! Much appreciated!

Some updates, I've brought my broken HDD to another mall which have more data recovery shops to get a second opinion on my HDD diagnostic.

I went to 6 shops, 5 of them tested it. Still as dead fish.

One of the shop plugged it long enough for it to be detected under some software called "Disk Utility" and it is detected as 2.2TB disk that needs to be initialized, which according to him, not a good sign.

Most of their comments varies, PCB board, ROM broken, FW corrupted.

However, all of them agreed that there's no clicking sound as claimed by the first data recovery shop I went previously.
The disk sounds healthy.

And all of them said that data recovery is at very high possibility (sometimes I just think they wanted my business) but it is not going to be an easy task and hence, as you have expected, costly.

And one shop actually shared that the price is not related to how much data they can retrieved, but how complicated the retrieving process is. Hence, even if they just managed to retrieve 1 file out of my HDD, they will still charge me full price of it unless they can't retrieve anything at all, then no charges.

So, I'm not going to gamble my money with it.

As a closure to my weeks and weeks of pain and headache (not to mention time and effort wasted), I will leave it be.

Maybe once in a while I might try and see if it does comes alive again (some actually shared that their drive works miraculously after 6 years) or I might just perform autospy on it.

So, its either I revived it or killed it 100%. Hahaha..

Hello unhappy_wd_user,

it's hard , that in one mall is a lot of DR shops.
It would be good, that you wait and ask forum members if someone know someone with reputable pro DR from your country or region.

Hi Jerovsek, thanks for your input!

I've been waiting for that "someone" that you mentioned, but I don't think there's a need anymore.

After being checked my 5 shops, it is pretty much concluded that my disk is dead.

There's a shop which gives me a pretty good explanations and diagnostic of why and what had happened to it.

He suspected (based on his experiences) that it is the ROM within the PCB that has been corrupted.

It can be caused by when we did not eject the disk before unplug it, which I admit I've done it before.

But most of the time, I only unplug it (without eject) when I've tried to eject but it keeps telling me that it is busy, try again later. And I keep trying but it keeps telling me the same thing. I have check I've closed all windows related to the HDD but somehow in the background, something is still connected to the HDD and I just unplug it.

So, the guy advised me if such cases happened, shutdown the computer before unplug it.

He have seen so many cases with WD on similar issue, especially with the Green and Blue series.

So, everything else is working fine, disk powering up and spinning, but since the ROM is damaged, there's nothing to tell the head what or where to read the data, hence my HDD is not being detected.

It just like a person in coma, heart beating, but brain dead.

So, to me, as a novice, I don't think there's anything else I can do further unless someone pro can guide me otherwise.

No one of the people you asked had a professional hdd diagnose tool like PC3000 and/or a DDA. That's the problem. So we assume the thread is closed and you'll wait for better times or forget the drive with the data and carry on... (to me the problem is just the price of pro intervention , express couriers do ship and pick everywhere if you don't mind crossing the borders....)

Yes, you are right!

I just couldn't justify the cost eventhough the data inside is valuable to me.

Considered this thread closed unless my lady luck decided to pay me a visit in future.