I have a harddisk of 250GB of Seagate which I got 3 years ago. My computer was off for 2 days as I had gone out, so when the third day I started my PC it gave me an error of "Enter boot media". I removed my harddisk and noticed there is not vibration in it which may indicated that there is no power supply, I also tried to substitute that harddisk with another and it worked. So there is no problem with the wires, I think there may be a problem with the power intake in the harddisk.
the problem is indeed the power intake to the motor of the drive.
the disk inside need it to turn around.
I noticed this in servers that aways run and only need a shutdown for maintenance and then not booting anymore.
this is perfectly possible.
there is no immediate sollution except replacing the drive (if they are in raid the raidcontroller will prepare the new disk as the missing disk ).
If you need data from that disk to be recovered then I advise you to ask this to be done by a specialised company who can work dustfree or do it yourself.
I did this once with a PC from someone at work who didn't make a backup from his drive.
the disk stopped spinning and I could hear some squeeking inside (as if oil was missing).
My first step was looking for the same 2nd drive and a 3rd drive.
I opened the drive (with gloves against dust and scratches).
Removed the disk-platter from it's motor.
I did the same with the 2nd disk.
Next I mounted the 1st disk-platter into the 2nd diskdrive (carefully between the 2 diskheads).
(the mount was not sufficient, it didn't work)
I mounted also the disk-controller (the motherboard from the first disk) onto the 2nd drive.
This made the disk readable and as soon as I could made a copy onto the 3rd disk.
The 2nd disk worked perfectly for a whole weekend without it's cover (open), no worries about dust going inside as the 3rd disk was mounted in the laptop and ready to be given back to it's happy owner.
I told the owner that If he needs this to be done by a company, he'll pay hundreds maybe thousands of € or $. And he payed me a nice bottle of Champagne. (underpayed yes, but it was my first experience with this problem).
hope this helps !
PS: I made a dustfree environment with just a plastic box a glass-plate for the top. Long plastic gloves glued through big holes on the side of it (to put your arms in). A third hole for a 12V Fan to suck air out. all the other holes were filled with foam from filters. so clean air goes in the box trough them and dirty air sucked aways trough the fan. This was a nice little project but I never needed it again since.
If the drive doesn't spin up, or make any noise, however faint, then the PCB is most likely faulty. The first things to check are the TVS diodes. If either of these is shorted, then there is usually an easy no-cost DIY fix.
You are right but, nobody other than electronic-geeks (with respect) could repair this, even the equipment is so costly !
I had a non spinning drive and changing (repairing) the PCB wouldn't have helped !
The only thing that helped was changing the squeeking motor or complete housing !
(it was so old that turning the disk with the hand, was like oil missing in your roller blades).
If the spindle motor is seized, or if the heads are stuck to the platters (stiction), then you would hear a very faint "spin buzz". This is the sound of the motor controller repeatedly attempting to kickstart the motor.