When I turn on my PS3 the green light stays on for 2 seconds and then just beeps 3 times and turns off.
How can I fix this?
3 beeps is a POST (ps3 equivalent) failure. It generally indicates a terminal problem with the unit and is most commonly caused by heat-related issues having caused the GPU or CPU to have become unseated.
Here is a guide how to fix it, I am not sure if it helps, but it will be good to try: https://www.ifixit.com/Guide/Fixing+Playstation+3+Green+Light+of+Death+(GLOD)/5163