Macbook someone spilled pepsi. Need advice?

Okay Since I am really new to macbooks. So my sister had one spilled pepsi on it one day and said it doesn't turn on. She said she took it to apple store they said it needs a new motherboard and was gonna cost her about $800 to fix. So she just bought a new one. I bought this one from her for $400 to help her out. Now I am stuck with this laptop. So its been a couple of months decided its about time to actually take a look at this. First thing is the computer actually starts up! keyboard works but doesn't light up. Okay so when it starts it shows up a white screen with an apple logo in the middle and a grey bar in the bottom and starts to load. Once it hits 100% it just restarts and does this all the time. I tried the Fsck to check the hard drive but of course fails that test. So im just thinking maybe im lucky and its the hard drive. I have a few options I was gonna do.

1) install a new hard drive
2) open up the laptop and see if theres damage to the motherboard physically
3) if it is indeed the motherboard and ima pop it in the oven see if that will resurrect it. (last option though)
only thing i can think of on what to do. As far as the motherboard was just gonna dump in the rubbing alcohol but the one that has 99% alcohol to clean the whole motherboard and every electonical part and see if im lucky and put everything back together and hope i am lucky? any advice on what else to check?

 

I'd go with option two, but Apple is probably right that it needs a new board. You can try to clean it since you probably aren't likely to make it worse. I think the chances that it's the hard drive seems pretty small, but if you've got an extra drive to test it with, it's worth a shot.

 

yea looks like its option 2. i checked the hard drive and there is nothing wrong with it. So it points out to hard drive.

edit:There were no burnt marks on the motherboard there was 2 brown spots. That once dipped in rubbing alcohol and with a little elbow grease at least 85% came off . Just gotta let it dry and hope it turns out good. and for some reason there was still some pepsi in the computer.

 

you can hold down the option key and at least get to the boot menu without a hard drive, assuming the keyboard is working

 

You can install the OS on an external and boot from that and see if it works. Did you try checking the ram? Everything sounds like the logicboard, but you never know. Did you try to reset the pram or the smc or reinstall the OS?