Hello.

 I was trying to repair a sata 1tb harddrive and had a 500gb harddrive that had a circutboard on the back that looked almost exactly like it. what i did was try and switch the boards out so i could use the TB because the original board had the smaller sata plastic plugin broken off, the metal was still there but there was nothing to back it up. Anyways after replaceign them nither would power on at all. ive pluged them up inside a desktop as well as a usb harddrive adapter.

I ran into another problem, /cry when i was trying to trouble shoot the problem on the TB the screwdriver(flathead) sliped and cut 3 cords below the board. i soldered them back together and swaped the boards back to their original hdd. but still nighter will power on. Before i switched both harddrives powered on, as for my 500gb it worked perfectly but after i switched and switched back it stoped powering on. ive tried cleaning the pads that connect the board to the harddrive to no avail as for the Tb harddrives board it doent look damaged enough to not power on and the disks on both drives are intact its just the circut board and the 4 wirepards under the Tb harddrive, but i think ive repaired that much because it was just a simple electrical connection.

I would relly like some help on this. did it fry both boards by trying to swap them?
If so what parts need to be replaced on the board?(i can solder, ive modded my psp before so i have experiance in micro tech.)