got exactly the same problem here. The pineapple arrived a few days ago. Everything worked fine fine for one night.
After one reboot (unplug) the next morning it didn't boot anymore.
Solid green and a faint of red.
Since then it's really a brick. Steps to unbrick fail due to the link not coming up.
I tested this on several computers. U,D,D,U,U also fails.
seems to be a hardware failure. I'll do the same and ask for exchange at shop@hak5.org.