You have a short or failure in one of the power lines on the board. The empeg has a number of jumpers dotted around the board marked variously as: 5V, 3.3V, 5V Analogue, 10V Analogue. Remove them all first. Then replace each voltage jumper one at a time and power on the unit. Check the power LED and the link LED until you find the jumper that makes it fail as it is doing now - it's that voltage line. Let us know here what you find.

Before you do this, remove the drives from the unit. Also, smell the unit to see if there is a burnt smell. Finally, give it a good shake to make sure there are no loose bits in there to make the damage worse (WITHOUT the drives, OK?).