iMac booting on primary monitor, but goes blank
My iMac was having issues with the backlight flickering, so I replaced the LED driver board which seemed to do the trick at first. However, now, when I restart the system, it starts to boot on the iMac’s display, but will then flicker briefly then blank out completely and show the login screen on my secondary monitor (which I had previously configured to act as my primary screen). If I press the Sleep button on the login screen then wake the computer back up, the iMac screen turns back on until I login.
Tried resetting the SMC and PRAM. Might it be some kind of driver/firmware issue on the replacement LED driver board? I definitely checked that it was the right version board before I purchased it.