Dead Powerbook G3, not powering up

Dear All.

I've just replaced the PRAM battery in my Powerbook G3 Wallstreet II 292mhz (with 192mb RAM, 8gb HDD, 20x CDROM, 14" TFT running OS X 10.3.9 thanks to Xpostfacto), and on putting it all back together it now will not power up.

When I plug the mains into the laptop, it wirrs up, the green LED comes on along with the fan, and after a few seconds it switches itself off. I've tried to do the same without the battery in but the same happens, if I try and power up without the mains then nothing happens. After this, if I try to boot it up using the power button, then nothing happens. The power button / keyboard seem to be ok as I can force the laptop to switch off in the few seconds its on for by pressing Shift/Fn/Ctrl and the Power button.

I reopened the laptop and made sure all the boards were properly seated on the logic board and put it back together again but I'm still having the same issue.

Can anyone suggest anything to help me get it back up and on it's feet?

Thankyou in advance for any help that can be provided,
Warm Regards.

Stu

PS. The original reason for changing the PRAM battery was due to the laptop forgetting it's time/date, forgetting which drive to boot up onto sometimes (causing the question mark / floppy disk icon syndrome), and not activating the backlight when booting into OS X.
PPS. I hope this hasn't been done before on the forum, I couldn't see anything when I searched.

My wallstreet G3 does the same thing as the PRAM is completely dead. It WILL turn on after it does the fan and green light thing. Just keep pressing the power button, man. Try holding it for a bit and pressing it repeatedly, it works for me.

Also you should try resetting the PRAM if you haven't already. There is a diagram on the back of the PB by the ports.