Swapping result

If you did swap the pcb's between the good and bad drives and either works, then that's pretty much tells the story. Your original bad drive is basically kaput, a hard h/w problem, just broken. Placing a good pcb on to it may have also burnt it out as it tried to correct the problem or it can't get far. Return the pcb back to their original drives and decide if you want some data retrieval service to have a go at it, but costly.

FYI- Use some Velcro strips or rubberized mats to place ext. drives on to reduce droppage. It's a good tip that can prevent simple falls.

tada -----Willy happy