Chosen Solution
My mother gave me this mac with this issue. If I manage to fix it, it’s as good as mine, plus it comes with me to college. Mom was trying to install an update on the Mac when this happened. The loading screen loads a tiny bit then it stays there forever. Since it’s stuck at that loading screen, I’m unable to use any button commands. This may not be related, but the only time mom turns the mac off is when she updates it. Although I have little to no mac knowledge, the one thing I can expect through my PC knowledge is that it may be a hardware issue. I don’t want to open the mac with my noob-level experience.
Do you access to another Mac? Your systems drive may just need a fresh copy of macOS installed. There are a few possible ways we can do this: The simplest is to create a bootable OS installer USB thumb drive from the other mac following this guide: How to create a bootable macOS Sierra installer driveWe can also connect your iMac to another Mac via FireWire cable then use Target Disk Mode so your iMac’s drive is accessible to the other mac Use target disk mode to move files to another computerAnd lastly, if you still have access to the original grey CD/DVD’s that came with your system we can install that version of OS-X and then upgrade to the newer macOS Sierra 10.12.x Here’s the needed OS installer for Sierra, jump down to Step 4 How to upgrade to macOS Sierra
