I cannot boot my 2009 20" iMac
I am having these same difficulties, as I cannot boot my 2009 20"iMac which prior to suffering a fall off my desk,was running OsX elCapitan and having 2 1Gb sticks of ram. After it fell it hasn't been able to boot and I am getting a file folder with question mark flashing. I've tried to restart in HW troubleshoot but got a brief green screen but then it powered down and did nothing. I then put in 10.6 leopard install disk 1 and when It booted in start-up mgr the only option was to start from disk 1 so I selected it and now it just keeps restarting over and over with nothing but a blank grey screen.