Unable to recover hard disk drive after failed formatting due to sudden power outage

Age can be a factor. If it's true that the hard drive is 11 years old, it's about time to replace it.

In my experience, any hardware that's is more than 5 years old can be unreliable. That's just me speaking from my experience.

With what you have already done, it would be best use of your time to replace the hardware. Any extra effort is just a waste.

Hard drives are inexpensive these days. Get one from a reputable company, Best Buys, New Egg, etc.

Practically, the disk is dead, but I've found a few things that could wring a little life off of a dead drive.

If your filesystem alone is the issue, you could run a tool that works device level, like shred in order to zero out the drive completely, and doing a reformat. I'd recommend a "full" format, and doublechecking by using a badblocks option (in linux) or chkdsk in windows with the appropriate switches - /b would work for ntfs, and /R for other filesystems.

In theory zeroing out and reformatting the drive kicks in the drive's own bad block checking and error correction, and I've kind of gotten a 'dead' drive that underwent a similar scenario running for a short time (then dying, then coming back to life, then dying again finally).

That said, you really also need to consider the health of the drive as a whole. Modern drives have a reasonable ability to self test. I'm a fan of gsmartcontrol since it highlights problem values, but I'd recommend running a short test, then if it passes a long test. If either disk health checks fail, you're better off binning the drive.

Smart Statistics are also handy - I've another answer that goes into detail on these, and if you can't get smart statistics, well the drive is also dead

Formatting only affects the data itself while disk recognition is handled by a chip inside the HDD. That's mean your formatting cannot be the cause as long as data and disk recognition are handled by different parts.

So the most probable scenario is the chip didn't supported the power loss, maybe he suffered from a temporary high tension (preceding the power loss in your house) that killed your HDD.