I just ran into this issue - blank (real black) screen, one brief flicker then back to black. Power LED blinks like the system just crashed, but blinks out a pattern of 10 short blinks and one long.
I replaced all the CHIP RAM thinking it was that, but what it really was turned out to be a bad single-wipe socket(kind of a redundant statement, they're all bad by default) on the U300 CIA.
Moral of the story: If chip swapping doesn't work, get rid of all the single-wipe sockets before you go any further, even if they look good.
