MacBook does not start w/o powersupply

[mullmann]

MacBook 2.16 GHz
2 GB RAM
MacOS 10.5.5

I have changed the HD to a bigger one and upgraded after this installation the OS from 10.4 to 10.5.5 with the firmware updates being recommended by the Apple Software Updater.

Since this the MacBook won't start without the power supply being connected. When I disconnect the power supply form the running MacBook it immediately does a hard shut down.

When I try to turn it on w/o the power supply the disc drive makes a short noise, the HD starts spinning for a second and the white LED in the front right corner goes on. However then the system just turns off.

When the MacBook is running on the power supply the white LED is actually off (I can't tell if this was always the case).

I swapped the old HD back in an still the same.

I did reset the System Management Controler (SMC) and still the same.

The battery is good (all green light light will go on if the little button is pushed) and the iStat Pro tool says load status is 98% and health is good.

I have no idea and the warranty is expired just two month :-(

Any suggestion and help is greatly appreciated,
thank you, Martin

[DeltaMac]

Try a known-good battery, maybe a friend's?
If there's no difference, even with a different battery (or you don't have access to another battery), then most likely you have a failed battery connector, or possible the mag-safe connector board (the internal part where your power adapter plugs in.) A trip to an Apple service shop will sort this out. Either of those parts are inexpensive (maybe about $20), and not too difficult to replace. Unless your battery needs replacing, a repair may be less than $100