24" Intel iMac. Rescued from a house fire. No direct flame contact, but smells of soot but looks new after a good clean. Hard drive has the click of death, so I've just now replaced it with a new 1TB disk. It booted on the first try. I then initiated a 10.7 install via USB flash drive. Install ran fine for first 30 minutes, then the system froze. Now the iMac will chime when booted but only to a blank black screen. There's also only 2 of 4 LEDs(to the right of the clock battery) lighting up, which shows that the second stage of the boot process that spins up the hard drive and flips on the screen is not initializing. Any ideas?