Dell 1525 Inspiron, won't start

My Laptop over heated today and I removed the back plate to gain access to clean out the fan ect... Once I tried to boot the computer up, everything flashed at me like always but then turned off, the screen remained black.
I’ve done a little research via googled and I have tried .....

1) Removing the AC power lead and the battery and switched them about to see if it would resolve, but resulted in the same issue as stated above.
2) Holding the power button down for 10/20 seconds without the laptop having power and with power. Then powering up.
3) I’ve pulled the HDD and the memory as instructed by the Dell support site (When power was disconnected) and booted, switch the memory about and booted a number of time. Everything was re-connected properly.

This is driving me totally mad as I need the laptop due to work and other reasons, I paid £550 about four years ago so it’s no longer under warranty, also none of the settings where changed before the issue began.

I would be grateful for any advice or assistance,So what is the possible issue that I’m having, is my motherboard fried or is it something else?
 
just like mine

am trying to find the sleep sw that hibernates the sys to bypass read the threads under tryingdad, maybe we can fix both
 
My laptop has been stripped and I would say I need a new motherboard, as one of the components (resisters or something) looks like its been blow as it’s a dark sticky residue
 
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