if your giving them power and they are not even spinning up I think your in trouble unfortunately
there is some good news though, if the PSU has killed the HDD circuits, its unlikely that platters themselves are damaged, so the data is probably still there, but without the circuits to spin them up, your shit outta luck, You do have options though:
If you can find other drives that are the same model, if you're careful you could switch the circuit boards to repair it and recover the data that way (no gurantees though)
or
If the data is critical, take it to a data recovery specialist, they generally cost a bit, but they do this sort of thing every day so it wouldn't take long to recover, which from your original description, there is a good chance they can get it all back.
This is why I have an online service to back up everything critical to a server in the US, cost me $5 a month for peace of mind (I have currently uploaded about 15gig, but it is an unlimited service and have about 50gig more to upload that is not as critical, so good value)