iMac A1311 won't power on with display plugged in

I recently acquired an old iMac that I am hoping to fix up and use for video editing. I don't know the history of the machine presently. It won't power on with the display cable plugged in. The connector doesn't look damaged. I suppose it could be a bad cable?

Got a little more info on the iMac. The LVDS display connector on the logic board was damaged by an inexperienced technician, which explains why the cable has to be unplugged for the computer to power on. I bought a replacement board on eBay that was advertised as working but gives the SOS beep code (3 short, 3 long, 3 short) to indicate a corrupted EFI firmware. Oddly enough the new board doesn't power on unless the display thermal sensor cable is unplugged. If it's just a matter of replacing the EFI chip, I might give that a shot...

Old, and I man say pre 2010 iMacs are not worth throwing money at.

harryb2448 said:

Old, and I man say pre 2010 iMacs are not worth throwing money at.

Click to expand...

I meant to post specs, this one is actually a mid-2011 Thunderbolt model: http://www.everymac.com/systems/app...inch-aluminum-mid-2011-thunderbolt-specs.html