Replaced Logic Board and can't get to boot screen. Suggestions?

Yes, I installed the RAM, which had been previously working on the old board.

To be specific about the beep, when I hold the power button down for three seconds, I then hear a single 3 second tone, followed by very very rapid flashing of the sleep light. About 10 or 12 flashes in 1.5 seconds.

Any idea if these flashes are too fast for beep codes, and if not, does this mean my new board is bad?

I also tried variations to test the RAM banks and the RAM. When no RAM was installed I heard the single beep and double flash as described above, however when either a single chip was in either bank or both chips were in different banks, when I restarted the screen remained off and it would not boot.

Oddly, I heard the happy start up chime only once when only the top RAM bank was in use, but still no boot. I was unable to repeat the chimes again, even after multiple restarts, after holding the power button down briefly to start, or holding the power button for 3 seconds, or while holding option+command+P+R keys.

strange..., i would only try to use the top ram slot, try to disconnect the pram battery and start the powerbook, try to power it on without battery. but to be honest, it doesn't sound good. maybe you should look around for a company that fixes gpu errors. search on ebay for powerbook and gpu - maybe you should get rid of the new. non working board and get the old one fixed

Thanks for the advice Markus. I ended up putting the old logic board back in and it started right up, so it looks like the "new" board has a problem.

thanks for the info, and don't forget to "accept the answer" - this moves the question from unresolved to resolved and can help others

Roger that Markus. A new board's on order. -- By the way, the 3 second tone and rapid flashing was confirmation of a PMU reset rather than RAM status codes.