hi Zajo, I know it feels bad that your hard drive has become such a pain. if you are plugging the problem hard drive as a slave to a working computer and it causes the computer to not boot at all, then its likely that the hard drive itself is causing the non-boot issue.
its possible that the hard drive's circuit board is damaged - causing a short circuit of some sort and preventing the motherboard from booting. I recommend you disconnect this hard drive, and lets look into possible options:
1.If your computer still has warranty, check and contact HP for possible options of computer check-up and repair-replacement. They might ask you to bring the computer to a service center.
If they would diagnose the hard drive to be the problem, ask for recovery options – assume that data recovery will come at a price
But usually, data recovery services will give you a deal “no recovery = no payment”
2. If your computer no longer has warranty from HP, remember that the hard drive might still have a valid warranty to its manufacturer. Check the brand, model, serial and product number of your hard drive. Hard drive manufacturers themselves offer data recovery services.
3. Also, you may want to try third party data recovery services
4. One last option for recovery is a diy approach!
Success is not guaranteed, and I personally have never tried this.
Supposedly, if the disk inside the drive is still intact and not damaged, its possible that something in the circuit board is damaged. This can be fixed by replacing the circuit board with an exact circuit board model and firmware number
Notice that the Seagate drive in the picture.
If you are to try purchasing a drive, the circuit board details should be the same model number, and same firmware number
This website supposedly sells hard drive and hard drive circuit boards of different model number and firmware numbers. HDD PCB, Hard Drive PCB For Data Recovery Needs! - HDDZone.com
An article in TomsHardware.com says replacing circuit boards is also one of the data recovery solutions done by hard drive manufacturers and third party providers. Supposedly, its not 100% safe to simply open a hard drive and replace the circuit board – as dust and other particles might get inside and interfere with the drive.
Goodluck on this, and let us know when you’ve got the data recovered / circuit board replaced.