could dust be causing my MBP to not start up?

so my MBP recently took a turn for the worst. it won't start up. pushing the power button just spins the harddrive for a split second then clicks off. a mac genius mentioned that it was probably my logicboard and an out of warranty cost for repair would run between $850-$1250. my renters insurance covered the cost for a new computer so i just went ahead and purchased a new i5 MBP 15". i removed my harddrive succesfully following ifixit directions and was able to migrate the data off the HD via pc tower to my new MBP.

so enough rambling here's my question: I discovered an insane amount of dust covering my logic board. could the dust be causing a short on start up? does this happen? what steps should i take to diagnose that there is a critical problem with my logicboard and not something minor that would be cheap to fix. i'd like to be able to salvage my original MBP without having to fork over $800.

thanks for any info whoever decides to help me out.

cheers.

jason