Good morning to you all.

I have same 820-01069-b board with no display after upgrading the RAM.
Removed the new RAM and put back Original RAM, No Display.
SMC and PRAM reset also no help.
Not connecting to External monitor also.
LED 1, 2, 3 ok. But the 4th LED not coming up.
No Apple chime.
The display is working well with another imac.
Nothing wrong with both power and display cables.
What could be wrong?...