I've come into Possession of a Fat PS3 S/N P-27430155-9 YLOD PLEASE HELP.

It has been sitting for years I do not know if it was working when it was stored or not. It has YLOD. It turns on Green Light Yellow light Red light and beeps three times. I would like to restore it. (Its already been opened and cleaned of dust while a-lot nothing was clogged heatsink wise) People who are much better at this than me where do I start?