Please, tell us what you attempted for us to make a NOT TO DO list.
I have a DA that from time to time loses its ATA66 channel. If i take the battery off a couple of days it comes back by itself...
Try unplugging the battery a couple days and try back.
I can't recall what I did to the other two iBooks as that was probably almost a year ago.
But in this one I changed an environment variable (load-base). The Mac OS ROM uses this to allocate memory for the trampoline and toolbox rom.
I changed it to see if the ROM would give an error of any interest.
Well, this is not an environment variable that should be touched. Open Firmware and the boot ROM that starts Open Firmware uses this as well. So it does not boot to a chime or even to a point where it can get keyboard input. Needless to say that means no resetting NVRAM or PRAM to clear out the value I set.
I'll leave it sit for a few days (with no battery and not connected to power at all). See if any of the stored power drains and the stuff resets it's self. (not counting on it. It didn't work on the other two either).
So don't change the load-base environment variable. Original value was 0x80000000 and I set it to 0x40000000.
BAD BAD BAD idea.