I was running a space AIO the other night.. and all seemed to be well.
It only has the 2mb onboard video.
I set the video to 1024 x 768 and 16bit colour.. which worked fine while running.
Shut it down.. tried to reboot the next day.. and screen was ... hmmm well it fires up.. but nothing there.. like no signal.
Now I know you can have too high a resolution to boot.
So I tried to do cmd opt P+R and does not work.
but ctr cmd power will reboot.
I have removed the battery.. I tried the cuda.. but that changed nothing.. the part I find funny is the machine will not respond to ZAP Pram.