elitebook only powers on with battery after ac adaptor has been plugged in

[Jon7773]

Hi there, apologies if this is in the wrong place.  I have an elitebook 2170p that I have recently stripped down and rebuilt with spare parts from a donor machine.

upon reassembly I have a power on issue that seems to defy logic.

If I detatch the battery and then reattach another battery the unit fails to switch on. even if I replace the original battery the problem remains.  The only way I can get the machine to work is by attaching the power cord... now you may think Ah it's the batteries... I certainly did, but then the strangest thing happens, once I remove the AC power the machine works fine, and will start on battery power alone, as if there is no problem.

the problem only rears it's head again once the battery is removed, then I have to go through the whole process of attaching the AC power cord again.  which means I can't take a spare battery out with me, as disconnecting means I will have a non starting machine.

I hope that someone can help me.

many thanks in advance

Jon

[Jon7773]

In addition to the original post, I have now put another motherboard into the machine, and it is all working fine.  so the problem it would appear is with the motherboard, I just wish I knew what was causing this as it's a shame for the motherboard to be just sitting there now gathering dust.