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Help!! My iMac screen is dark!!!

Posted: Fri Apr 22, 2016 2:06 pm
by anne murray
I've been writing a report today on my iMac running Yosemite. I left the computer to take a break. When I returned the screen was dark and only the cursor was visible. I tried to restart the computer, but it does not respond to the power button. I can move the cursor, but that's all.

I'm grateful for any advice; I'm trying to get this report out today.

Many thanks.

Re: Help!! My iMac screen is dark!!!

Posted: Fri Apr 22, 2016 2:22 pm
by Stephen Hart
If you can't see anything on the monitor, of course, you can't use the normal restart command.

A single click of the power button only wakes the Mac if it's asleep. To force a restart, you have to hold the power button down for several seconds. You should hear the iMac hard drive spin down. Wait a minute and then press the Power button to restart the iMac.

If you get nothing from that procedure, you may have to just pull the plug. Wait a minute or so and plug back in. Then press the power button to restart the Mac.

Note that either of these procedures may well cause work to be lost.
The only other way to deal with a situation like this that I know of is to get your Mac showing in Screen Sharing on another Mac, and restart it properly that way. You might be able to save the last-saved version of the file by using File Sharing on another Mac and copying the file in question to the other Mac.
If you have Time Machine running, you should have a copy of the file one hour or less old.

If you can get the Mac restarted, and you were using Microsoft Word, there's a secret way to retrieve Word's autosave file in case what you see when you reopen Word is old. Reply here and I might be able to help with that situation.

Re: Help!! My iMac screen is dark!!!

Posted: Fri Apr 22, 2016 3:20 pm
by anne murray
I was in the kitchen and heard the computer restart - more than an hour after I tried to restart it. Apple said it restarted because of a problem, which Apple label "Sleep wake failure." The report from Apple was too lengthy and technical to ask anyone to review.

So, now my concern is what would cause such a failure - what greater concern do I need to explore?

Re: Help!! My iMac screen is dark!!!

Posted: Sat Apr 23, 2016 6:51 am
by Stephen Hart
Here's a possible scenario:
A sleep-wake failure might mean that the iMac went into sleep mode on schedule when you took a break. But something went wrong and it got stuck, unable to wake properly again.
You used the power button to force a restart. And that process took a very long time. One way that could happen is if an app is trying to complete a process and can't.

I'd be very sure to keep your backups current. It's possible that some more or less routine diagnostics could turn up something.
How old is the iMac?