The PowerBook 3400c left the market in 1997. That it worked until Christmas is a testament to the quality and durability of Macs. However, a computer that old may have any number of problems.This one thing for certain:
The most recent OS that can be installed on your computer is MacOS 9.1. You cannot install MacOS 9.2.1.
Beyond that, no one can diagnose your computer's problems without physical access to the machine. Having said that, my best guess is that your battery has given up the ghost. Although you probably need a new battery, there is no way to tell that your old battery is the cause of your problem. If it is not the problem, then the $90 that you pay for a replacement battery is $90 down the drain.
My suggestion to you is to take your computer to a local shop that works on Macs. Have the technician diagnose your problem(s) and perform any needed repairs including replacing the battery if necessary.
