Late 2009 Unibody MacBook not booting. Strange clicking and scratching noise.

So this is a pretty bad situation. Ok so I am a 12 year old Mac person, I am really good at Macs at my school (know as much as the 3D Animation teacher) and I am stuck at this problem on my moms 2009 MacBook. So yesterday her computer would not wake from sleep mode. I forced shut it down, then I rebooted it everything was fine. Then later when I was booting Mac OS X 10.8.3 on an external hard drive (she doesn't like me touching her files) the computer made a clicking and scratching noise. Everything immediately stopped responding in the force quit window and I let it sit there not responding for an hour. Came back still not responding... Shut it off manually and then unplugged the external hard drive and computer is now stuck at the grey screen. I reset the pram or whatever it's called. So since I'm the only one that knows ANYTHING about Macs in my house they blamed me. Ok so conclusion time I think it's the logic board that's dead, it's not a kernel panic or can't find boot device because I have it set to the internal partition. I asked my computer teacher (with macs a lot) she had no idea. All the hardware is the original I have not upgraded the ram or hard drive or video card or anything so I'm going to tomorrow reset the smc scm or whatever. (system control management). I'm going to have to pay for all the repairs, so I would love it if somebody could help me save some big bucks (hey I'm not a bank) and not pay for it but give some advice on what I could do to fix it. I would pay up to $100 dollars to get it fixed for parts. Logic boards are like $200-$650 and if its not broken that would be great. My dad has not found out yet (he would go ballistic and send me to a public school, has done it before we're not rich, if we were I wouldn't be posting here) and I hope I can fix it and my mom said she would let me be the tech guy at the store we might open (it's either that or the dress department :\ ...) Well enough of me blabbing on here are the specs.

Ram: 2GB

Hard drive: 250GB

OS: 10.8 Dev preview 3 (I know shouldn't installed it on hard drive...)

Mac: 2009 Unibody Macbook (Macbook6,1)

Processor: Intel Core 2 Duo

Video card: Nvidia something can't check because its broken already establish :)

That's it thank you guys. I feel weird I'm supposed to be the one helping people... :( That was the only mac besides my dads.

-JP