No output on display
I have an iMac (mid 2011 21.5) where the screen will no longer come on at all. The HDD had failed, I replaced it and put it back together but now I get no output. I cannot check if an external display would work because I don't think the iMac's display anything till booted on an external display (cant boot the Mac cause the HDD is new with no OS).
The connectors for the screen look to be seated right and I have tried to re-seat them also.
All 4 diagnostic LEDs light up on the Logic board but I still get no output on the screen.
Any advice would be appreciated.