I'll be impressed by whoever can answer this one.
My friend came to me with his xbox that began experiencing problems a while ago. The completely standard box (not modded in any way) began failing to boot up. The box would power on fine (fan and everything could be heard firing up) however there would be no audio, no video and the front LED flashes green. At this stage it is not possible to eject the DVD tray. Pressing eject only initiates a reset whereby its tries to boot again.
This said, it is however possible to get the box to boot on VERY RARE occassions by repeatedly pressing the eject button and interupting the current boot up.
I pulled the box completely apart and inspected all the hardware. Power supply seems fine and i couldn't see any burnt out tracers or anything. i cleaned all the contact points (ground points between the m/board and the inner metal casing) up of any scum using iso propyl alcohol (a luxury of working in a research lab), I put the box back together but the problem persists. The owner reckoned I might be related to the DVD-ROM, I tried my DVD-ROM and the problem persists.
From here I pulled the Xenium ICE outta my Xbox (having recently received my GOLD SP its time was up anyway!) and installed it in faulty box via the solderless adpater. The install went perfectly and pressing eject booted up to Xenium OS first go. I added the retail kernal as a launch item, made sure the drive was locked and launched the MS dash but go the same thing.....no audio, no video flashing green, chip LED off (which is I what I present it to).
Thinking that the MS dash files may be corrupted I FTP'd over a fresh copy (that I've used previously to restore my own M$ dash) however the problem persists.
From there I FTP'd a copy of the Unleash X dash onto the C: and it boots up perfectly fine. Strangely though, from within Unleash X I can boot the MS dash perfectly everytime.
Any takers?

?
I've looked up the all the trouble shooting manuals I can find but have come up with nothing thus far.
PS. My Xenium GOLD install went flawlessly. i soldered in the removable d0 wire, slapped the gold on my existing pinheader and the install is sturdy as a mountain goat!!!
Hats off to the Xenium team for a top quality product!!