Dell Inspriron n5010 shuts down after 10-15secs ! Help!

My friend has a Dell Inspiron N5010. Unfortunately it is out of warranty now.



The problem is that the laptop just simply powers off within 15-20 seconds of powering it on.



- It's not a hard disk issue since no matter where I am it will power off, even if in the BIOS.

- I have tried using only 1 ram stick and using it in each slot, no change. Though I haven't checked using a different ram stick, I doubt both of the sticks would go bad suddenly.

- I had disassembled the whole thing and reapplied thermal paste on the CPU/GPU heatsink. The fan works fine. No use.

- I tried to boot into the Dell diagnostics menu and it passes a few tests before powering off.



Is there anything else I can do? The only option I can think of now is to give it to Dell. They'll charge quite a lot just for checking and then whatever the costs for replacing what's gone bad.