Apply power to the hard drive and nudge the stepper arm (DON'T PUSH IT TOO FAR). If it doesn't immediately spin up, cycle the power. The head is likely stuck to the platter.

As awful as Miniscribes are I really like the noise those 20mb drives made. MAke sure you give it a good non-destructive exercise after however to make sure they drive won't immediately crap the bed on you.