Won't power up all the time

I have been handed an 06 15" Pro with the C2D 2.16

The problem I'm having is that if I have the battery installed (fully charged) it won't power up. Not even the slightest indication of working, IE no fans, lights, hdd, dvd nada.

I'll connect the wall charger and I get a dim green light, dim amber if the battery is in need of charging.

Remove the battery and plug in the charger a couple of times and it goes to bright green (dim green till then) and act's like nothing was wrong. Boots right up, runs great and when I install the battery while it is still on it shows up. It will charge it if it is low. I can then pull the wall charger and it will run fine off the battery.

I can even shut down and restart off the battery if I don't let it sit too long.

I have checked the battery on another system and it works fine. Used another battery on this one and it has the same problem.

Charger is working fine on all machines and used others on this one with same results.

I did find out that if this one won't power up (battery installed) and I get the dim green light and then use the charger on another machine first it will then go right to bright green when I reconnect it to this one.

I am using the troubled one as I type, have done all the tests and reset everything I can think of (please don't tell me to do the basic things like pram, check/clean connections and such, it has been done to death) but have not run into anyone else that has seen this problem.

One last thing I noticed is when I do shut it down I get the spinning cartwheel for a short time then it shuts off.

Any idea's?

Ended up replacing the hard drive and the power board, hard drive (Seagate) took way to much power to fire it up even in a newer machine and the power board I am guessing became weak from it.