Notebook problem!

CAT-THE-FIFTH

I bought this second hand notebook off Ebay. It was in a semi-working condition. Basically the battery connector was burnt(I wonder why??) but the rest of the notebook was ok according to the seller. When I received the notebook it did boot up ok and even booted into Ubuntu. However it seems to shut off after a fixed time period(a minute or two). Took the notebook to bits and put some new thermal compound on the cpu and the same still happens!!
Cannot be overheating of the cpu then but what is the issue?? Can anyone help??

albertross_2

Does it work without the battery?

CAT-THE-FIFTH

It boots up on the AC power supply but then shuts down after 1-2 minutes!!

albertross_2

Is that with the battery removed?

any fans in it not spinning?

CAT-THE-FIFTH

All the fans and lights turn.The notebook boots up and all the normal stuff comes on the notebook screen.It will boot into Ubuntu linux and after a minute shuts down. I tried removing the hard disk and it still does the same thing. I went into the bios and it still does the same thing after a similiar time period!!