I recently bought an iMac 21.5 inch emc 2308 from a guy. He told me that Apple had told him it needed a new power supply, I bought one and replaced it. Now, I'm new to Macs, so I don't know much. But the iMac still doesn't respond when I push the power button. I took it apart again and noticed there is no hard drive on board either. My question, what will an iMac typically do if no hard drive is on board and you push the power button? I can see the LEDs on the logic board and only one stays lit when I push the power button. I would appreciate any help/advice anyone could give me.