How to get my internal Harddrive to spin externally?
The Stepper motor in a harddrive will not run with power applied just to the logic board. The logic board needs to activate the motor through the SATA connection. If you want to power the motor at full speed, you need a stepper motor driver and connect it to the raw motor connections (by removing the logic board)

See Make hard drive stepper motor run 7200 rpm for a way to make it run.