Im just a simple noob when it comes to this.. I just borrowed a friends chipped xbox yesterday and Im pretty sure I ruined it:/..
So this is what I did, and I know it was stupid but still.. I didnt get a game working from the HD that i really wanted to play. So, what I did was go into Flash bios, and said, hey why not try this. So I did, and I had no idea what it would do, but when it said erasing "something" I paniced and turned the xbox off as quickly as possible.
When I tried to restart it, I had the exact same problem as you do.. And now I checked out what bios do and stuff, and on a guide on how to do this I saw that it said, Warning: If done incorrect you could ruin your chip.
And as it seems I really did. So that suckes, but there doesnt seem to be anything I can do now but get the chip replaced. And I guess thats what you have to do to.
Still, I would think there should be some way of just resetting the bios or something, shouldnt it?