[Macworld]

Post your comments for Mac troubleshooting: What to do when your computer won't turn on here

[redgeminipa]

My former iMac did this a couple of times.

I unplugged it for a few minutes. Then I tried turning it on. Usually ended up waiting a few more minutes and tried again. By the third time, it would boot and be normal for months.

I probably should've tried the SMC reset.

[nginear49]

My daughter's iMac (2006) did this, problem was a broken power button. Apple Genius diagnosed it, said a new logic board was required for $800. I wired in a new pushbutton and all is well.

My mother-in-law's iMac (2007) is now doing the same. I opened it up and found no problem with the switch. Tried all the Apple fixes (same info as this Macworld posting) including the steps to reset the SMC. No help. Next stop is the Apple Store. If a new logic board or power supply is needed, this nice 24" computer is destined for the junk pile, and my mother-in-law will no longer have a computer - there is no way she can afford a new one of any brand, let alone Apple.

[rogerowens]

Warning: if you reset your Mac's SMC, be sure to reset the date and time in System Preferences, ASAP. Do not open Mail and other date sensitive apps before you set the date.

[PReinie]

My August 2008 13" MacBook (not Pro) sometimes does not power up. This has only been after a shutdown, and I wait until the screen goes black before closing the lid to prevent Sleep taking over from shutdown.

The only way I can get it to boot up is to remove the PS (AC power) and then remove the battery for at least a few seconds (several minutes might be necessary. That lets all power from capacitors drain.).

Then restore the battery and PS cable and it has powered up every time.

Fortunately my MacBook has the easily removable battery with the flip-switch and pop-out battery. Why they went away from that made no sense to me.

[Paulmsl25-gvp]

My iMac (dec2012), gets very noisy after pause or stop. Fan runs fast and never stops until i switch on again. During use no noise
any suggestions? thanks Paul

[duncanpt]

This keeps happening to my wife's MacBook Pro. The "reset the SMC" guidance is rubbish- when the thing does choose to restart, it has nothing to do with the instructions which I follow to the letter. It appears to be entirely random: At some point when a capacitor has discharged or something, the machine starts charging once again and will start. Until that happens the most annoying thing is that the only status light on the machine, which is the LED in the magsafe connector is happily green, even though truthfully it should be orange or off. I cannot believe how Apple gets away with making machines that are so resistant to simply being turned on or charging their batteries.

[pigeontech]

Got my 2011 27" core i5 iMac last weekend. First time Apple user and loving it. Bit concerned now though having read a few of these comments and having experienced a total refusal by it to power up after a brief shut down to clean dust from the entry and exit holes from the previous owner who clearly didn't love her Mac as I'm sure I'm going to

I was all set to call Apple Care when I read the SMC routine. Note, I was getting absolutely nothing from the iMac when I pressed the power button. No fan whirr, nothing. It was like it was totally dead. All cables were correctly inserted and going to a proven live socket.

I followed the SMC routine :

Shut down the computer.
Unplug the computer's power cord.
Wait fifteen seconds.
Attach the computer's power cord.
Wait five seconds, then press the power button to turn on the computer.

and hey presto...it works again!

Now I'm a happy Apple user again:)