Yosemite Won't Boot - Advice Requested
Seeking your advice!
Well, so I woke up this morning and my iMac (running Yosemite) won't boot up. It gets to the Apple logo and then the machine dies completely.
I can boot from an external drive. And once I do that I can access files on the internal drive (one that won't boot).
I can't seem to get safe mode or diagnostics to do anything, they start to launch but then machine dies.
I'm confused as to whether I have a bad drive, or a corrupted OSX. I can access files on the drive that won't boot, so that suggests OSX as the problem.
Any thoughts you may have on this matter will be most appreciated. Thanks!