Computer won’t post with internal HDD attached

I’ve come to boot up my computer this morning to a problem that’s making me scratch my head – If I have my internal 500GB HDD attached, my PC won’t even POST or make it to the BIOS splash screen, no beeps or anything. The drive was working perfectly yesterday, then all of a sudden this.
I’ve verified that the cables are good, as I’m using them right now with an old 250GB HDD, and I can hear the drive spin up when I’m starting up the computer, no clicking, it’s never had a SMART failure either. However, I don’t have another computer to test it in. It’ll boot up with just a SATA power cable in that hard drive but if I attach the data cable, no dice. I’ve tried booting into a Linux live medium and tried hotswapping it to no luck, tried the same thing in Windows, also doesn’t work.
Is my drive totally dead?
Answer #1
However, I don't have another computer to test it in.
Well, Another option is to buy an external enclosure and try that (Using either an OS installed on another HDD or a Live CD)
Is my drive totally dead?
Most likely!
But you could verify it^
Hope you didn’t have any important/non-backed up data on it (As it’d cost you a fortune to have it recovered!)
Answer #2
I thought about the external enclosure, I guess it’s the only way to get it working now, as I have an enclosure with a dead drive in it.
And about that… I have 465GB worth of un-backed up data on it because of above reasons…
Answer #3
I thought about the external enclosure, I guess it's the only way to get it working now
If that’s even possible!
as I have an enclosure with a dead drive in it.
That’s a very inaccurate statement. It’s an internal HDD, So it’s not sitting in an “enclosure”
An external enclosure is basically a box with a USB output, Which you put the HDD in, Nothing further. It’s not made to replace the HDD’s original cover/circuit board. All external HDDs are just an HDD in a box, There are no “Native” ones.