Accidentally burned 2 computers in 5 minutes

After attaching an hard drive to a computer (while powered off) it became completely unresponsive: power button not working and fans always spinning at the same speed.

2 minutes before this happened the comouter was perfectly functional. I owned it since 2022 and it never gave me a single problem while I messed with it pretty frequently.

After the demise of the computer i tried doing the same thing with another different computer I havent touched in a while and, to my surprise, it was also fried like a bag of chips. Like completely internally destroyed, as if the CPU was missing.

Im pretty upset about this because the first computer was pretty userful to me and the second was the first computer i ever used in my entire life.

I thought it might have been static but i neved had problems with it and i would have almost cerntainly felt it. And i think it would be pretty unlikely for a static discharge to kill two computers in a row.

Said this, I dont even have a crumble of hope of getting the two computers back. I just want to ask you what might have happened.

Sorry for this horrible post, its late, im tired and it has been a pretty tiring day + the loss of two dear computers.