HP 8470P - Turns on, starts boot process then turns off

Hi Guys,
I am new here - I am quite technical, but I have a bit of a weird one where my HP 8470P laptop fires up, goes past the F1 setup screen and then appears to show another screen (much like the screen that asks if you want to resume startup - not sure what it says) but then turns off.
I initially thought it was a power adaptor or battery as when I connect the battery it begins to fire up then turns off.
I have tried an alternative power adaptor, with the same results.
I'm not quite sure if it could be CMOS or motherboard issue?

Many Thanks in advance.

 

Sounds like an overheating issue or other hardware fault.

 

Thanks for the response.
I did wonder, but how is it getting that hot in such a short period of time?

 

Thanks.
No it gets to the menu, but then turns off more or less afterwards.

 

A cpu without a heatsink or working fan, will go critical very quickly.

It could also be a broken motherboard trace or solder joint in the power circuit. You turn it on, current flows, it expands as it gets warm and breaks the connection. Could be any number of causes.

CMOS battery simply supplies power to retain the BIOS settings when the PC is not connected to power. It has nothing to do with the operation of the computer. You can completely remove the battery and it wouldn't matter.

 

OK, so tonight I've stripped the laptop down and cleaned fan assembly, and cleaned off thermal paste and replaced - with the same results so it appears it's something more serious.
I'm not really sure where to go with it now as from what's been said its likely to be a motherboard issue then?

 

I've actually tried leaving it disconected for 10 or so minutes previously and the fault remains.
I am now wondering if the motherboard is faulty. Not really sure what diagnostics to do now tho.