If it doesn't stay on after you remove the hard drive then you have another issue, and my guess would be the YLOD. To get back in a working state you'll have to reflow it, just look it up on YouTube if you don't know what that is. Once you get familiar with the process it becomes really easy. I buy PS3s off eBay and fix them myself. Reflowing and applying new thermal paste ( I use Arctic Silver 5) is only half the job as the YLOD will happen again, it will only be a matter of time. To extend the life of the PS3 I install a fan controller to keep a constant high volume of air flowing though the power supply and heatsink. It's called PS3 EZ Chill.