Never mind. This morning I had an eureka moment. I opened the TiBook, disconnected the optical drive, lifted it a little, enough to see the PRAM battery connector. I then disconnected it, and closed the TiBook.
Then I plugged the AC adapter in, pressed the power button and it booted. [
] ]'>So indeed it was the PRAM battery. Now, of course, if left without power, the TiBook won't remember date/time settings, but it's a non-issue, as it'll be connected to the Internet through my home network all the time. What's more, I don't have to rush for a new PRAM battery and I can enjoy this spotless PowerBook for the time being.
I believe this same trick works for G3 PowerBooks like the Lombard and the Pismo, so if you happen to 'liberate' these guys and they don't seem to boot and you suspect it might be a dead PRAM battery, try disconnecting it before giving up.
Cheers!
Rick