9 beeps/SOS (3 short, 3 long, 3 short) and iMac not booting

The iMac in question is a 2009 3.06 GHz model, originally with 4gb of ram. It had been upgraded to 6gb by a friend of mine who gave it to me.

Essentially, when pressing the power button, the mac will beep morse SOS instead of booting; 3 x short, 3 x long, 3 x short. This repeats indefinitely. During these episodes, it ignores any and all keyboard inputs. Occasionally I can get it to boot, though most of the time it just goes right into beeping.

I’ve opened up the system to get a look at the status LEDs, and when it’s beeping, only the first two are lit, which indicates that the motherboard is getting power just fine. When it manages to boot, all four light up.

I’ve tried to reset the NVRAM, PRAM, SMC, and so on. I’ve replaced the PRAM battery, even though the existing one tested at nearly full capacity.

I’ve swapped ram extensively, this does not help but on one occasion the system booted right up after removing one of the sticks. This never occurred again, however, despite repeating the removal of the same stick.

This beep code is not covered in the apple support pages at all, the only thing similar is the article on EFI corruption, but that beep code is 3 x long, 3 x short, 3 x long; the inverse of what I’m hearing on my machine. Even if it was EFI corruption, I have no way to restore it, as apple does not offer a firmware restoration CD for the 2009 iMacs, nor am I able to reliably boot into external media anyway.

In addition to this, whenever the beeping is occurring, the screen remains blank and off. Nothing displays, not even the backlight turns on.

I’ve gone as far as trying different outlets in my house, all of them lead to the same result. I’ve left it off, plugged in and unplugged, for extended periods of time, and yet the issue persists.

The DVD drive will accept discs but often just spits them right back out after spinning them up.

I’m just hoping someone here can help me get on the right track.

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