Today my Intel iMac (mid-2008) suffered a heavy software crash, effectively leaving me no choice but to turn it off, as the shutdown process would hang forever. I held down the power button several seconds, until it went off.
Unfortunately getting it back up was not that easy. I would hear the startup chime, but after that the screen would just hang, completely gray. I could hear the CD in the drive spin up and down again after a few moments. Keeping the mouse button pressed, the option key down etc. – all sorts of tips you get on the Internet – did not work.
First I suspected the stuck CD was the problem. The Intel iMacs do not have an emergency eject hole for the slot in drive, though. Looking for a solution to my problem, I searched for all sorts of keywords I could come up with related to an emergency eject, but to no avail. All the tips and hints you get – including those on Apple’s site – relate to older models that still had such a hole for a paper clip.
After a while I remembered a similar situation a few months ago, albeit without the stuck DVD part, when I was ready to take the whole thing to an Apple partner for checkup. In preparation for that I unplugged it from power, but did not take it off the desk immediately. For some reason I later decided to give it another shot and plugged it back in, just to see it boot up normally. I did this again today and after 20 seconds without power (actually I just switched of the power strip), it would boot just fine.
Only after that did I find this Apple support document which actually does not really help unless you search for SMC or PRAM reset on Google and dig for a while. So hopefully I saved you some time, if you read this.