Black screen and fan running full- bore

Question

Computer was running fine when I closed the lid (no shutdown) to put it to sleep for the night. Next morning as usual I opened the lid but the screen showed no signs of waking up. The battery was apparently dead so I plugged it in. Pushed the power button and the fan came on full-bore and the screen never showed a sign of coming to life. Restart, no help. Attempted to zap the PRAM but no signs that the key commands were recognized. (2 month old keyboard after the computer took a nasty fall and the old one popped out damaging the ribbon cable connector). Inserted a disk I thought would allow the computer to boot off of, it did some spinning but no change in computer's operational status. Eject button or key commands now fail to get the CD out. The only way to restart is to press power button until computer goes off then press again to start. The fan just keeps on running but nothing on the screen.
Connected computer to external monitor, no help, even after restarting. The monitor is connected to a G4 platinum tower so I know it works.
I also don't see a way to eject the inserted CD manually as command E, eject button, won't eject it.
I'm at a loss! First time a Mac has gotten the best of me. None of my years of little trick gathering has helped.

Answer 1

I tried holding down the trackpad button (forever), no help.
Was the computer all the way off (no lights, fan, sounds, etc.)?
Hold down the power button for ten seconds to shut everything off. If that doesn't do the trick, unplug the power adapter and remove the main battery. Then put them back, hold down the trackpad button, and start up. Is your CD ejected this time? If not, shut everything down again.
If it's a bootable CD, try booting to it after resetting the PRAM: hold down the p and r keys while starting up, and keep holding them down until you've heard three or four startup chimes (if you hear any). After the chimes, release those keys and immediately press the c key to force the PB to try to start up from the CD. Any luck? If the CD isn't a bootable one, of course there's no point in trying this step.
I tried restarting in the firmware mode (command, option, O, F), no help.
I don't know anything about that, so I'm no help with it either.
Before the black screen problem I noticed the battery would run down to zero overnight when the lid was closed and computer was sleeping. I'm not sure this is normal.
Definitely NOT normal, and this is undoubtedly a clue to what's wrong. Something is allowing the battery to drain when it shouldn't. (Batteries, actually, since the backup battery will also drain completely within 10-15 minutes after the main battery, if no AC adapter is connected.) This strongly suggests a short circuit to me. But tell me: do you always leave the Powerbook sleeping on battery power overnight, without the AC adapter connected? Or does the battery drain even with the adapter connected? That would point to a fault in the adapter or in the charging circuitry inside the Powerbook.
A short circuit might leave marks on the surfaces that are coming into contact and shouldn't be. Check the inside of the bottom panel, the logic board surface components, the underside of the keyboard, and whatever else you can see for visible signs of shorting. If you can see that something has been shorting against the inside of the bottom panel, as has occasionally been reported here, cover the affected spot with a small piece of electrical tape to insulate it. Tighten all visible screws — you'll need Phillips #0 and Torx #8 drivers. Look for empty screw holes: a screw wandering around loose inside could cause untold damage.
My AC adapter appears to work fine, it, like the battery, is only a couple of months old. Thing ringlight shows normally.
By "normally," do you mean orange while charging, green when the battery is fully charged, and never flashing, red, or off? That's what normal is.
If you haven't tried to recharge your internal backup battery as described in step 6 of the "Testing Backup Battery" article I linked above, do. Of course you won't be able to see or set the date and time or verify that the battery has been charged, but you can at least do what is supposed to charge it and hope for the best. Again, if it is discharged and hasn't been recharged in the course of all your machinations so far, everything else you do is doomed to fail until it gets recharged.
If after that nothing has changed, you might try disconnecting the backup battery from the logic board. Doing so will sometimes allow a PB to start up that has been prevented from doing so by a stone-dead backup battery. Consult the iFixit Guide for your particular Tibook model to find out exactly where the backup battery connector is in it. In my 1GHz Tibook, it's a small white connector under the right-hand Shift key, with red, white and black wires attached.
If none of this helps, I'm afraid you're due for a trip to the repair shop.