Powerbook G4 not starting, battery not charging

Right, so I have checked this issue on many blogs, but can't quite find the answer.

Here's the gist:
I have a PowerBook G4, A1138, 1.67Ghz, (yes, it's old.)
Anyway, I bought it refurbished and it was working find for over 6 months, but suddenly the battery stopped charging.
I managed to wiggle the adapter in once or twice getting it to charge again, but now nothing is happening anymore. I can still see the green light flicker on the battery if I press it.
Of course, I also cannot turn on the computer anymore, given that it's dead.

Here's what I've tried:
1. I tested a different charger. It's not the chargers. They work fine on another ibook.

2. Reset the PMU by taking out battery, unplugging charger and holding down start-up button for 10sec. Nothing.

3. Took out RAM, left it out a bit, put it back in. Nothing.

4. Gave it some good hits, Russian style (read somewhere that might do it, but...) Nothing.

5. Am currently attempting to charge the computer over night without the battery in to see if the PRAM is still ok.

I know it could either be my PRAM, or the DC-in (but doubt that, I did previously repair the DC-in on the ibook and the entire process of the DC-in frying up was a lot slower, if you wiggled the charger the battery would always still charge a little, so don't think it is the DC-in).
It could be the logic board of course, but how will I know?
Could it simply be the battery?

Any advice?
Thank you!!!!

For starters I would think that the battery has in fact died on you

Yes, but shouldn't the computer still turn on if I take out the battery and just plug in the charger?

It might be a matter of time for it to do so, ie which is why am leaving it plugged in over night, but thought I'd ask.

I'll report back on that tomorrow, because if of course it doesn't turn on that would mean my PRAM bat is also gone, is that correct?

Cheers!

No success with that either...

Just been told it's either the DC-in or the logic board...how do I know which one of the two it is...are there any diagnostic tests to run for this...