I bought an HDD from Western Digital and the power adapter had broke and you cant buy them other wise you have to buy a whole new HDD how stupid is that????.....
It'll help that they weren't in use, a HDD under load (spinning) is far less stable. If you get em working, rip important data off then straight away, it might be the first and last time they work
I have purchased and sold many used drives. I always made sure they had available warranty time in case something went wrong. I think I have had only one fail.