First, let’s find out if the problem is that your Mac won’t start up, or that it won’t turn on – those might sound like the same thing, but there’s actually a big difference.
Press the Power button on your Mac. If you don’t hear a startup chime, you don’t hear any fan or drive noise, and there are no images, video, or visuals of any sort on your display, then your Mac isn’t turning on at all. You’re not even getting to the point where it refuses to start up.
A Mac that doesn’t turn on calls for a different approach to one that doesn’t start up. If your computer doesn’t turn on then you need to do the following:
i) Check your power connection
Don’t be the cliché: check that the power is on and the Mac is plugged in correctly. Or if it’s a laptop, be sure that the battery isn’t dead – and if it needs charging give it a while to attempt to charge before concluding that it isn’t going to work. If your MacBook won’t charge read this.
ii) Try a different power cable or adapter
It may be that the fault resides with the power cable. If you’ve got a friend with a Mac power cable that fits your machine, try it to see if that solves the problem. If it does, it could be a simple fix that involves finding a secondhand power cable on eBay (although we advise against buying third-party power cables that aren’t made by Apple, as they are much more likely to be faulty and possibly dangerous).
If you recently had a power cut, that could be responsible: your power adaptor could have been damaged in a power surge and you may need a new one.
Finally, it’s possible that the cable is loose, and pulling it out and plugging it in again will solve the problem. But we doubt it will be that easy.
iii) Disconnect all accessories
Unplug all the accessories (such as printers and USB hubs) attached to your Mac. It could be that one of your peripherals is causing problems with the startup sequence.
If you recently installed new RAM or a new hard drive in your Mac (both of which are something you can only do with old Macs), make sure they are correctly installed and compatible. (If possible, reinstall the old memory or hard drive and see if that helps.)
If none of those steps work then it’s time to move onto the next stage.