Question I made a horrible mistake. | Acer 5740 / Model NO. MS2286

[BreakerLol]

So, I wanted to fix the Laptop from my little Brother.

He plays games on it and it randomly turned off.
He stayed it was doing that like every few hours.
I thought it overheated. And it was full of dust.
After I cleaned it up, plugged only the board in, pressed the button and it turned on!
So I wanted to connect the screen to see if everything works because this computer is very hard to take apart.

Here comes my mistake. I turned it off, but I didn't unplug it...
It doesn't turn on now. The light that indicates that it gets power(It is always lit when the computer gets some sort of power) doesn't light up.
It doesn't turn on with a charged battery ether...

I already took out the ram and tested it on another surface...
What should I do next? My Father would have soldering and a Multimeter to test the board.
My Father said he wanted to test the connections on the next day.
But what should we look for? I would appreciate every help...

The worst thing is that I have a gaming desktop. So I don't have a laptop for school.
So I always borrowed his when I needed one...

I would appreciate every help or links to threads that could help me.
Thanks

EDIT:
I also want to say that we bought this Laptop used! And it had an Overheating problem before! So it overheated probably many times.

 

[hang-the-9]

The cost to replace that 10 year old system would be as cheap and much easier that buying a replacement motherboard for it. Just look for another system of the same model and you can simply move the drive over to it. To check the board and try to replace parts in the motherboard is very hard without having the schematics of it and those are pretty much impossible to get outside of the company that made it.

 

[BreakerLol]

I found the Schematics online but I can't really understand them!
And I found the problem! I hope it is the only problem this thing has.
Its the Bios Chip(MX25L1005) for the EC.
My Friend has a Programmer and he will give it to me soon.
I already found a bios online, so I hope I can fix the machine.
It has the correct power but doesn't send any firmware data so the machine wouldn't boot or light up

With the help of my Father, I already got the chip off. So now its waiting time for me

 

[hang-the-9]

It is very very unlikely that the issue is with the BIOS chip itself.

 

[BreakerLol]

Well i looked in the internet for a bit and I found multiple posts from people that have that problem and fixed it that way. It could work

 

[RolandJS]

After getting it working, always use an external usb-powered cooling assembly (one giant fan or twin fans) -- those things really help.