you could try re-flashing the OS on the chip burn the OS (I would suggest OS2b2) to a CDR with the file name recovery.bin and flip the little switch on the chip, it should come up in recovery mode, it will just flash at you for a while and then shut off ...
Be sure to take the CD out and flip the switch back before turning it back on.
And you should at least get the Xenium OS menu, if that does not work, and you know 100% that both the box and connections are good, then you might have a bad chip.
btw, just curious what version of box is it?
I hope this helps