Before you do all that there are two things to try:

1. Try a different USB cable.
2. Try a different power supply.

What happens is that the disk powers up from two sources - if either fails to supply the needed power the external will fail to boot. I've had repeated issues with my Lacie "Porsche" designed externals (both the 1TB and 0.5TB) and have had replacement power supplies sent to me from Lacie (2x on the 1TB).

-- John