OK, I went through these steps. Three LEDs lit, external monitor works, but screen completely black. Found a deal on a used screen, swapped it out. Power up the Mac, the screen lit up long enough to show the apple on a grey background then died, now same symptoms as before.
Did I just kill another screen?
What next, logic board, power supply or inverter?
Should the logic board detect the panel even if the inverter and backlight isn't working?
Thanks,
Steve L.