I really need some advice here - please!

Have a Seagate Barracuda XT 4000DX000
It died suddenly and was not showing up in Windows or MB BIOS.
The drive would spin up, no other noises and just keep spinning.
Weird thing was when you powered it down, it seemed to spin a lot longer than usual until it stopped.

So I got a donor drive, swopped the PCB and BIOS chip. Exactly the same issue.
Next I swopped the heads and now it spins up, the heads move across the platters, no damage on platters or heads but makes unusual noises and then stops spinning.
Please see video below. Gets interesting mid way through.
The wind noise is the laminar air flow filter sound but you can clearly hear the odd sounds.
Its not really the typical beeping sound, its also not grinding, its kind of a singing drive?
I don't have a PC-3000 to do any fancy diagnostics.

I hope someone can offer some advice! Please!!

VIDEO LINK:
https://streamable.com/tpdizy

Sorry, but I’m not going to sugar-coat this.

Basically, everything you have done is wrong.

Firstly the drive almost certainly didn’t have a heads problem in the first place, given that it did not click or spin down. It was also a waste of time changing the PCB, for the same reason.

Secondly, almost certainly something went wrong with the superfluous head swap, whether it be an incompatible donor or the procedure itself.

Thirdly, and most destructive you have let it run without a lid on, so there’s no “air cushion” to allow the heads to float above the platters but leave them to touch and scrape the platters (the “singing”).

Sadly you’ve already done all this DIY crap before coming to ask for advice. I’m afraid this may be too late for this drive

_________________
PC Image Data Recovery
http://www.pcimage.co.uk

New!! HDD-PCB.COM for all your PCB and donor HDD requirements!

Please tell us that's your own personal drive and no a customers

There are just far to many unknowns to provide much help on this, head and pcb compatibility, rom state and service area condition just to mention a few. Needed more tests and checks with the original hardware before bits were swapped out. If your data is important, reassemble it with the original parts and send it to a pro. PCimage and most have an open drive charge for just this sort of thing for a reason.

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Data Recovery Services in the UK.
https://www.usbrecovery.co.uk/

Thanks for all the advice but I would really like to know what I should have done in the first place aka what was wrong with the drive and what should have been done?
I only ran it with the lid off after doing everything and having no luck at which point I was about to bin it anyway.
The drive is not important, its just an experiment to see what was wrong with it.

You should have connected up a serial interface to the 4-pin COM port and report the output from the drive via that.

No point doing that now, I bet all you'll see is a bunch of "servo 007" errors.

As you say you've nothing to lose, why not try putting the original heads back? Assuming you've stored them safely in a comb, without them touch each other?

_________________
PC Image Data Recovery
http://www.pcimage.co.uk

New!! HDD-PCB.COM for all your PCB and donor HDD requirements!

Hi, I am only learning. I am 17 years old and want to know how to recover drives.
So I am finding damaged drives and trying to get the data back. They are drives that don't contain anything important.
I even bought some off ebay as damaged.
I have the original heads safely on a comb and will return them to the disk. At least I am practicing that along with getting good at bios swopping.
Clearly a long way to go still!
Now to learn about 4 pin COM and serial output.
Thank you very much for the help.